Download Evaluation of Health Care Operating Rooms as Wet/Dry

Evaluation of Health Care Operating Rooms
as Wet/Dry Locations
Final Report
Prepared by:
Melissa K. Chernovsky, Ph.D.
Joel E. Sipe, Ph.D.
Russell A. Ogle, Ph.D., P.E., CSP
Exponent, Inc.
Bowie, Maryland
The Fire Protection Research Foundation
One Batterymarch Park
Quincy, MA, USA 02169-7471
Email: [email protected]
http://www.nfpa.org/foundation
© Copyright Fire Protection Research Foundation
October 2010
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FOREWORD
A key area of debate in the most recent revision cycle of NFPA 99, Health Care Facilities has
been the topic of electrical environments in hospital operating rooms and whether they need
to be classified as a wet location or dry location.
The present edition of NFPA 99 (2005) requires the governing body of the facility to determine
if operating rooms are “wet locations” and therefore require special protection—usually either
isolated power-supply systems or ground-fault circuit interrupters (GFCIs)—against electrical
shock. However, there are two opposing schools of thought on establishing this designation
requirement, with the debate attempting to balance the need to provide a safe environment
for patients and operating room personnel while at the same time providing a risk based
solution and not over-designing the electrical distribution system.
This study defines and analyzes the hazards associated with hospital operating rooms to clarify
the classification type (i.e. wet location versus dry location) of their electrical environment.
This includes a review of the existing literature on fluid spills and electrical hazards in the
operating room, a gap analysis for missing information, and a proposed risk assessment method
for hospitals to use to evaluate the proper classification of an operating room.
The Research Foundation expresses gratitude to the report authors Melissa K. Chernovsky,
Ph.D., Joel E. Sipe, Ph.D., and Russell A. Ogle, Ph.D., P.E., CSP, with Exponent Inc. located in
Bowie, Maryland. In addition, the Research Foundation appreciates the guidance provided by
the Project Technical Panelists, and all others that contributed to this research effort. Special
thanks are expressed to National Fire Protection Association (NFPA) for providing the funding
for this project.
The content, opinions and conclusions contained in this report are solely those of the authors.
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PROJECT TECHNICAL PANEL
Rich Bielen, NFPA 99 Staff Liaison (MA)
Ken Dungan, Risk Technologies (TN)
Jan Ehrenwerth, Yale University & ASA (CT)
Doug Erickson, ASHE (VI)
Joe Murnane, Underwriters Laboratories (NY)
John Petre, Cleveland Clinic (OH)
Marcus “Sam” Sampson, MN Dept of Labor & IAEI (MN)
Jeff Sargent, NFPA 70E Staff Liaison (MA)
Walter Vernon, Mazzetti & Associates (CA)
PROJECT SPONSOR
National Fire Protection Association
Thermal Sciences
Study Regarding the Electrical
Classification of the Hospital
Operating Room Environment
Study Regarding the Electrical
Classification of the Hospital
Operating Room Environment
Prepared for
Fire Protection Research Foundation
1 Batterymarch Park
Quincy, MA 02169
Prepared by
Melissa K. Chernovsky, Ph.D.
Joel E. Sipe, Ph.D.
Russell A. Ogle, Ph.D., P.E., CSP
Exponent, Inc.
17000 Science Drive
Suite 200
Bowie, MD 20715
October 6, 2010
 Exponent, Inc.
Doc. no. 1002230.000 C0T0 1010 MC03
October 6, 2010
Contents
Page
List of Figures
iv
List of Tables
v
Acronyms and Abbreviations
vi
Executive Summary
ix
1
Background and Introduction
1
2
Literature Review
4
3
2.1 Conditions in a Hospital Operating Room
2.1.1
Clinical Studies and Medical Literature
2.1.2
Evidence of Fluid on the Floor during Surgical Operations
4
5
13
2.2 Study of the Volume of Surgery in the United States
2.2.1
Introduction
2.2.2
Classification of Surgery
2.2.3
Volume of Procedures by Surgical Category
13
13
14
15
2.3 Electrical Safety in the Operating Room
2.3.1
Electrical Hazards - Macroshock and Microshock
2.3.2
Electrical Safety Standard Origins
2.3.3
Electrical Safety Practices
2.3.4
Electrical Power Systems in the US Medical Industry
2.3.5
Electrical System Design Practices and Commentary in the Medical Industry
2.3.6
Comparable Foreign Electrical System Standards in the Medical Industry
2.3.7
Electrical Equipment Design Practices
17
17
19
21
22
25
30
32
2.4 Incident Reporting of Electrical Related Injuries in an Operating Room
2.4.1
Medical Incident Reporting
2.4.2
Workplace Injury and Fatality Databases
2.4.3
Trends in Adverse Event Reporting
2.4.4
Literature Citations of Electrical Incidents
34
34
45
46
50
Gap Analysis
3.1
55
Operating Rooms as Wet or Dry Locations
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4
3.2 Adverse Event and Incident Reporting
3.2.1
Database Information
56
56
3.3 Electrical System
3.3.1
Prevalence of Grounded vs. Isolated Electrical Systems across the US
3.3.2
Electrical System Costs
58
58
59
Risk Assessment Methodology
4.1
5
62
Risk Ranking Based on Spill Size
66
Summary
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iii
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List of Figures
Page
Figure 1. Fault tree for an electrical shock hazard in a hospital operating room
66
Figure 2. Fault tree for an electric shock hazard in a hospital operating room including
example liquids and possible modes of liquid release for consideration in the
risk ranking analysis based on spill size
69
Figure 3. Event tree for an electric shock hazard in a hospital operating room for the risk
ranking analysis based on spill size
70
Figure 4. Data presented in the SFPE Handbook 4th Ed., pool thickness as a function of
an unconfined, fixed quantity of water spilled on tile or concrete floor from a
discrete height: (purple circles) water on concrete from 0.5 m height (blue
diamonds) water on concrete from 1 m height, (green triangles) water on tile
from 0.15m, (red squares) water on tile from 0.9 m
72
Figure 5. Pool diameter as a function of liquid volume assuming a circular pool as
estimated from the polynomial fit trend line of the SFPE empirical spill data
for a spill of water on concrete from 1 m presented in Figure 4; The blue
squares represent sample volumes of liquid selected in the sample calculation
(Table 10) of probability of exposure
73
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List of Tables
Page
Table 1. Terms Used to Characterize Blood Loss
6
Table 2. Blood Loss in General Surgery
7
Table 3. Blood Loss and Transfusion Data for Several Types of Surgery
7
Table 4. Irrigation Usage in Several Types of Surgery
9
Table 5. Observed Frequency of Blood Splash during Operating Room Surgical
Procedures
11
Table 6. Surgical Groups by ICD-9-CM Codes
15
Table 7. Procedure Volume by Surgical Category
16
Table 8. Procedure Percentage of Total Volume by Surgical Category*
16
Table 9. List of States using Adverse Medical Event Reporting Systems
41
Table 10. Sample Calculation for a Single-Event Exposure in a 50 m2 room
74
Table 11. Sample Calculation to Determine Annual Risk based on the Probability of
Exposure to a Liquid Pool
75
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Acronyms and Abbreviations
A
amperes
AAMI
Association for the Advancement of Medical Instrumentation
AHA
American Hospital Association
AIA
American Institute of Architects
AIMS
Advanced Incident Management System
AHRQ
Agency for Healthcare Research and Quality
ANSI
American National Standards Institute
APSF
Australian Patient Safety Foundation
ARF
Area Resource File
ASA
American Society of Anesthesiologists
ASHE
American Society for Healthcare Engineering
ASRS
Aviation Safety Reporting System
BLS
Bureau of Labor Statistics
BS
British Standard
CMS
Center for Medicare and Medicaid Services
CFOI
Census of Fatal Occupational Injuries
DOD
Department of Defense
ECRI
Emergency Care Research Institute
EKG
electrocardiogram
EMC
electromagnetic compatibility
FDA
Food and Drug Administration
GAO
Government Accountability Office
GFCI
Ground Fault Circuit Interrupter
HCUP
Healthcare Cost and Utilization Project
HEA-ELS
Technical Committee on Electrical Systems
HTM
Health Technical Memorandum
IEC
International Electrotechnical Commission
IEEE
Institute of Electrical and Electronics Engineers
IOM
Institute of Medicine
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IPS
Isolated Power System
IRIS
Incident Report Investigation Scheme
IT
Isolating Transformer
JCAHO
Joint Commission on Accreditation of Healthcare Organizations
L
liter
LIM
Line Isolation Monitor
m
meter
MAUDE
Manufacturer and User Facility Device Experience
MDSR
Medical Device Safety Report
MHSPSR
Military Health System Patient Safety Registry
MHRA
Medicines and HealthCare Products Regulatory Agency
NASA
National Aeronautics and Space Administration
NASHP
National Academy for State Health Policy
NEC
National Electrical Code
NEISS
National Electronic Injury Surveillance System
NFPA
National Fire Protection Association
NHIS
National Health Interview Survey
NIS
National Inpatient Sample
NPSD
Network of Patient Safety Databases
NPSA
National Patient Safety Agency
NQF
National Quality Forum
OR
Operating Room
OSHA
Occupational Safety and Health Administration
PMA
Pre-Market Approval
psi
pounds per square inch
PSRS
Patient Safety Reporting System
RCD
Residual Current Device (European nomenclature for GFCI)
ROP
Report on Proposals
SFPE
Society of Fire Protection Engineers
SMDA
Safe Medical Devices Act
SOII
Survey of Occupational Injuries and Illnesses
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SRE
Serious Reportable Event
STF
Slip, Trip, or Fall
TGA
Ageing Therapeutic Goods Administration
US
United States
VAC
volts alternating current
VHA
Veterans Health Administration
WHO
World Health Organization
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Executive Summary
In the most recent round of code development for NFPA 99, Standard for Health Care Facilities,
which was scheduled to be released in 2009, an area of debate emerged in the Report on
Proposals and the Report on Comments. The debate involves areas of health care facilities,
particularly operating rooms, and centers around two philosophies. Health care and occupational
health professionals indicate that an operating room has the potential to be a wet location,
because there is the possibility of standing fluids on the floor and/or other areas, such as an
operating room table, and therefore, there are potential hazards and associated health risks to the
doctors, nurses and patients within the facility room. Health care facility managers, however,
indicate that there is not an established loss history, and therefore question why an electrical
system should be installed to protect from a hazard, when it is not needed or wanted due to the
extra installation and maintenance expenses. The debate was not settled during the 2009 revision
cycle, and the 2009 edition was ultimately returned to the technical committee and NFPA 99 was
placed in the annual 2011 revision cycle.
The motivation for this study is to provide a comprehensive view of the hospital operating room
electrical environment in order to facilitate hazard analysis by an individual hospital, to establish
whether a particular operating room should have a “wet procedure location” or “dry location”
electrical classification. Conditions in the operating room can vary dramatically based on many
factors, such as the type of surgery, collection methods for blood and fluids lost, and use of
irrigation fluid. As a result, it is difficult to assign a single classification to all operating rooms.
This report reviews the existing literature on fluid spills and electrical hazards in the operating
room, and provides a gap analysis for missing information.
A risk assessment method is proposed for hospitals to use to evaluate the proper classification of
an operating room. The recommended model is a risk ranking method based on the volume of a
potential spill or liquid release and the subsequent liquid pool size. This method determines the
annual probability of exposure to a liquid pool in an operating room.
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1 Background and Introduction
During code development for National Fire Protection Association (NFPA) 99, Standard for
Health Care Facilities, scheduled to be released in 2009, a key area of debate emerged in the
Report on Proposals (ROP) and Report on Comments (ROC) documents. The debate involves
areas of health care facilities, particularly operating rooms, and centers around two philosophies.
Health care and occupational health professionals indicate that an operating room has the
potential to be a wet location, because there is the possibility of standing fluids on the floor
and/or other areas, such as an operating room table, and therefore potential hazards and
associated health risks to staff and patients exist. Health care facility managers, however,
indicate that there is not an established loss history, and therefore question why an electrical
system should be installed to protect against such a hazard, when the system is not needed or
wanted due to installation and maintenance expenses. The debate was not settled during the
2009 revision cycle, and the 2009 edition of NFPA 99 was returned to the technical committees
and delayed to the 2011 revision cycle.
The current edition of NFPA 99 (2005) requires the governing body of the health care facility
determine if operating rooms should be classified as a “wet procedure location.” NFPA 70,
National Electrical Code (NEC), provides the following definitions:
Dry Location: A location not normally subject to dampness or wetness. A location
classified as dry may be temporarily subject to dampness or wetness, as in the case of a
building under construction.
Wet Location: Installations underground or in concrete slabs or masonry in direct
contact with the earth; in locations subject to saturation with water or other liquids, such
as vehicle washing areas; and in unprotected locations exposed to weather.
Wet Procedure Location: Those spaces within patient care areas where a procedure is
performed and that are normally subject to wet conditions while patients are present.
These including standing fluids on the floor or drenching of the work area, either of
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which condition is intimate to the patient or staff. Routine housekeeping procedures and
incidental spillage of liquids do not define a wet location.1
Areas classified as a wet procedure location require specific protection against electrical shock,
such as isolated power supply systems or ground-fault circuit interrupters (GFCIs). Presently, it
is not clear whether the procedures and situations probable in a hospital operating room should
be performed in an area classified as a wet procedure location or in an area classified as a dry
location. Considerations must be made to provide a safe environment for patients and staff,
while providing a risk-based solution to prevent over design of the electrical distribution system
within the operating room.
In the 2011 NFPA 99 ROP, the Technical Committee on Electrical Systems (HEA-ELS) is
evaluating a proposal with the recommendation to require a risk assessment to classify an
operating room as dry.
The objective of this research project is to define and analyze the hazards associated with
hospital operating rooms, in order to clarify the wet procedure location or dry location
classification of the electrical environment to assist HEA-ELS in the upcoming 2011 revision
cycle with a recommended risk assessment methodology.
The following chapters investigate, compile and evaluate associated operating room hazards in
an effort to provide a framework for developing a risk analysis methodology to be applied to
hospital operating rooms with a broad range of usage. Specific hazards associated with
situations that could occur during particular surgeries were considered.
Medical literature, manuals and texts are identified and information summarized to enable
classification of typical surgical procedure and situational groups for use in an operating room
risk assessment. Operating room usage across the United States (US) is summarized for the past
5 years. Several medical and health injury and incident databases were identified. Current
electrical design practices used in the medical industry by the US and foreign countries are
1
National Electrical Code, p. 28, 2008
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summarized. A gap analysis of the available data provides recommendations for the types of
data needed to develop a more robust risk analysis methodology. Following the gap analysis a
recommended risk assessment methodology is outlines, followed by a project summary.
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2 Literature Review
This study provides a comprehensive view of the hospital operating room electrical environment
in order to facilitate hazard analysis by an individual hospital to establish whether a particular
operating room should have a “wet procedure location” or “dry location” electrical classification.
A literature review was conducted to collect and summarize applicable information relating to
electrical safety in a hospital operating room. Hospital operating room usage was evaluated,
including factors that may lead to a wet or dry environment, as well as typical failure
mechanisms that could lead to increased risk of electric shock in a wet environment. Advantages
and disadvantages of electrical systems recommended for use in both wet and dry environments
were reviewed, as well as current design practices and policies in domestic and international
operating rooms. Additionally, the literature review provides data to determine the prevalence of
applicable injuries and deaths due to electric shock incidents.
2.1 Conditions in a Hospital Operating Room
The purpose of this section is to investigate the probability of the presence of an electric shock
hazard associated with liquids in an operating room.
Documented incidents of electric shock and equipment malfunctions in a hospital operating room
associated with the presence of liquids have occurred. For example:
•
In the early 1970s, a urologist was burned on the eyebrow, using a scope while standing
on a grounded floor and performing ground-referenced electrosurgery in a saline-soaked
environment. The urologist was wearing conductive booties over bare feet at the time of
the incident.2
2
Hyndman Bruce H, “A Thirty-Two Year Perspective on a Clinical Engineer’s Contributions to Patient Safety,”
IEEE 2004.
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October 6, 2010
•
In 1997, a stopper detached from an urimeter collection bag, causing fluid to cascade
over an extension cord power tap on the operating room floor, causing a power failure
affecting the entire operating room.3
•
In 1993, an accidental spill of a fluid container onto a blood pressure monitor caused a
malfunction of the blood monitor. A replacement monitor was not available, causing
harm to the patient.4
The presence of liquid on an operating room floor has been determined to be an important
electrical safety factor, as liquid can reduce the resistance between the human body and the
ground, presenting a danger of ground fault shock. Ground fault shock can occur when a live
wire in a piece of electrical equipment makes contact with a conductive component of the
exterior. Human contact with the electrified equipment while contacting a grounded surface can
result in a ground fault shock, which can lead to serious injury or death.
2.1.1 Clinical Studies and Medical Literature
In order to quantify the probability of a wet condition existing in a hospital operating room, a
search of the medical literature was conducted to gather information on relevant liquid spills. In
addition to the limited published research on liquid spills and electrical safety in a hospital
operating room, information was gathered from medical studies in various related areas. The
information collected can be grouped into four categories:
•
Patient blood and fluid loss;
•
Irrigation fluid usage;
•
Blood contamination of medical staff; and
•
Blood and fluid spray and splatter.
Data in each category is directly related to electrical safety, but was collected for different
reasons (i.e., patient health, hazardous material exposure and disposal, etc.). The data presented
3
Nixon MC, Ghurye M, “Electrical failure in theater-a consequence of complacency?” Anaesthesia, V52: 88–89.
1997.
4
Singleton RJ, Ludbrook GL, Webb RK, and Fox MA, “The Australian Incident Monitoring Study. Physical
injuries and environmental safety in anaesthesia: an analysis of 2000 incident reports,” Anesthesia and Intensive
Care, V21:5:659-663. 1993.
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in this section does not give a complete quantification of the amount of fluids present in the
operating room or the probability of a spill, but represents a survey of the available literature.
Information was also gathered on documented liquid spill events, which is presented in Section
2.1.2.
2.1.1.1
Patient Blood and Fluid Loss
The reviewed literature indicates that surgeons are familiar with typical blood loss associated
with particular surgical operations. The evaluation of blood and fluid loss levels is critical to the
life safety of the patient, therefore, effective monitoring and maintenance of fluid levels during
surgery is required. In many surgical operations, significant amounts of blood can be lost. An
average size adult body contains approximately 5L of blood.5 A 40% loss of blood (2L) can be
life threatening. Blood loss can be characterized by defining several severity levels. A list of
terms commonly used for characterizing blood loss is given in Table 1.
Table 1. Terms Used to Characterize Blood Loss
Term
Definition
Source
Normal
Above Normal
Excessive
0-500 mL
500-1000 mL
>1000 mL
Shorn, 20106
Hemorrhage
>500 mL
Shorn, 20106
Massive Blood Loss
1 Body Vol in 24 hours
50% Body Vol in 3 hours
150 mL/min
Stainsby et al., 20067
Minor
Moderate
Major
Catastrophic
500-750 mL
750-1500 mL
1500-2250 mL
>2250 mL
Fortunato, 20008
5
Grocott MP, Mythen MG, Gan TJ, “Perioperative Fluid Management and Clinical Outcomes,” Anesthesia and
Analgesia, V100. 2004.
6
Schorn MN, “Measurement of Blood Loss: Review of the Literature,” Journal of Midwifery and Womens Health,
V55:1. 2010.
7
Stainsby D, MacLennan S, Thomas D, Issac J, “Guidelines on the Management of Massive Fluid Loss,” British
Journal of Haemotology, V135. 2006.
8
Fortunato Nancymarie, ed. Berry and Kohn’s Operation Room Technique, Ninth edition, Mosby Missouri, USA,
2000.
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The terms in Table 1 give an upper bound to the amount of blood reasonably expected to be lost
on a frequent basis during common surgical operations. Attempts are frequently made to
measure or estimate the actual amount of blood lost during surgery. The results of several
studies for blood loss in surgical operations are shown in Table 2 and Table 3.
Table 2. Blood Loss in General Surgery
Volume
Source
0-600 mL
Ishihama et al., 20109
749-3670 mL
Boldt et al., 200610
0-5600 mL
Spence et al., 199011
Table 3. Blood Loss and Transfusion Data for Several Types of Surgery
Volume of Blood
Type of Surgery
Source
2250 mL
Transfusion during vascular surgery
Miller, 200512
1479 mL
Transfusion during liver resection
Miller, 200512
1800 mL
Transfusion during hip arthroplasty
Miller, 200512
5490 mL
Transfusion during spinal fusion
Miller, 200512
1246 mL
Transfusion during prostate surgery (1)
Miller, 200512
1717 mL
Transfusion during prostate surgery (2)
Miller, 200512
10 mL/kg/hr
Abdominal surgery
Grocott et al., 200513
100-7000 mL
Spinal fusion surgery
Szpalski et al. 200414
400-1500 mL
Cardiovascular surgery
Friedel et al., 199115
9
Ishihama K, Sumioka S, Sakurada K, Kogo M, “Floating Aerial Mists in the Operating Room,” Journal of
Hazardous Materials, V181, 2010.
10
Boldt J, “Fluid Management of Patients Undergoing Abdominal Surgery – More Questions than Answers,”
European Journal of Anaesthesiology, V23. 2006.
11
Spence RK, Carson JA, Poses R, McCoy S, Pello M, Alexander J, Popovitch J, Norcoss E, Camishion RC,
“Elective Surgery without Transfusion: Influence of Properative Hemoglobin Level and Blood Loss on
Mortality,” American Journal of Surgery, V159. March 1990.
12
Miller Ronald D, ed. Miller’s Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
13
Grocott MP, Mythen MG, Gan TJ, “Perioperative Fluid Management and Clinical Outcomes,” Anesthesia and
Analgesia, V100. 2004.
14
Szpalski M, Gunzburg R, Weiskopf RB, Aebi M, eds. Haemostasis in Spine Surgery, Springer, New York, 2004.
15
Gallandat Huet RCG, de Geus AF, Mungroop HE, Borgstein NG, Keane T, Pierce JTM, Karliczek GF, Eijgelaar
A, “Blood Use in Adult Cardiac Surgery – Extrapolations from the Carola Data Base,” in Friedel N, Hetzer R,
Royston, eds. Blood Use in Cardiac Surgery, Springer Verlag, 1991.
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75-2000 mL
Laproscopic splenectomy
Matteotti et al., 200616
1102-2544 mL
Liver surgery
Solomon, D. E., 199117
465-1930 mL
Spinal surgery
McNamera et al., 199118
186-3317 mL
Spinal surgery
Heller et al., 199119
1386 mL
Liver resection (1)
Seeber and Shandler, 200720
685 mL
Liver resection (2)
Seeber and Shandler, 200720
18.4 mL/cm2
Liver resection (3)
Seeber and Shandler, 200720
569 mL
Prostatectomy
Seeber and Shandler, 200720
637 mL
Cystectomy
Seeber and Shandler, 200720
134 mL
Mastectomy (1)
Seeber and Shandler, 200720
352 mL
Mastectomy (2)
Seeber and Shandler, 200720
149 mL
Mastectomy (3)
Seeber and Shandler, 200720
68 mL
Vaginal hysterectomy
Seeber and Shandler, 200720
215 mL
Hepatectomy
Seeber and Shandler, 200720
Typically, blood lost is collected and does not reach the floor. If careful collection methods are
not employed, however, pools of blood and bodily fluid could form from dripping or spilling of
collection containers. As a result, these reported blood loss volumes are the quantity of fluid
which could reasonably be involved in a spill accident.
2.1.1.2
Irrigation Usage
In many surgical operations, irrigation fluid is used to clean an incision or body cavity.
Irrigation is also used to clean contaminated wounds,21 to achieve hemostatis and visualize a
problem, and to reduce bacteria count, in various types of operations, such as neurosurgery, ear,
16
Matteotti R, Assalia A, Pomp A, “Splenectomy,” in Assalia A, Gagner M, Schein M, eds. Controversies in
Laprosopic Surgery, Springer Verlag, 2006.
17
Solomon DE, “Induced Hypotension and Isovolemic Hemodilution,” Spine: State of the Art Reviews, V5:1.
January 1991.
18
McNamera MG, Garcia FJ, Johnson RG, “Blood Loss in Lumbar Surgery: Prevention and Replacement,” Spine:
State of the Art Reviews, V5:1. January 1991.
19
Heller M, Transfeldt E, Cohen M, “Blood Loss and Transfusion in Patients Undergoing Spinal Surgery,” Spine:
State of the Art Reviews, V5:1. January 1991.
20
Seeber P, Shandler A, Basics of Blood Management, Blackwell Publishing, 2007.
21
Abouzahr M, Wider TM, “Prevention of Splashing During High Pressure Irrigation of Contaminated Wounds,”
Plastic and Reconstructive Surgery, V98. September 1996.
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nose, and throat procedures, the treatment of wounds, and the treatment of burns. Typical
volumes of irrigation fluid for several types of operations are provided in Table 4.
Table 4. Irrigation Usage in Several Types of Surgery
Volume (mL)
Type of Surgery
Source
6,000-12,000
Joint arthroscopy
Fortunado, 200022
1800-1900
Hip and knee replacement surgery
Singh and Kalairajah, 200923
2,000-4,000
Cystoscopy during bladder surgery
Fortunado, 200022
3,000-6,000
Transurethral prostatectomy
Fortunado, 200022
High pressure irrigation systems can operate at up to 2 bar24 (28.9 psi), flow up to 2L/min25, and
pose several risks. Irrigation fluid can splatter and drip, which poses contamination issues to
staff, as well as electrical safety issues if fluids reach the floor. If large volumes of irrigation
fluid are used, collection and containment is also an issue. Suction canisters are often used to
collect irrigation fluid, and accidents can cause these canisters to spill their contents.26 Some
hospitals use self-contained fluid waste management systems, which can hold up to 40L.26 In
some cases, containment bags are used to collect irrigation fluid during jet lavage of foot and
ankle wounds.27 If proper care is not exercised when handling suction containers, fluid waste
management systems or containment bags, they all pose a significant spill hazard.
2.1.1.3
Blood Contamination of Medical Staff
Much research has been conducted on the frequency of blood contact with operating room staff.
Many studies were motivated by a desire to characterize the risk of disease transmission to
operating room personnel, who can be exposed to blood and fluids. The available medical
22
Fortunato Nancymarie, ed. Berry and Kohn’s Operation Room Technique, Ninth edition, Mosby Missouri, USA,
2000.
23
Singh VK, Kalairajah Y, “Splash in Elective Primary Knee and Hip Replacement,” Journal of Bone and Joint
Surgery, V91:8. 2009.
24
Bars C, Schnabel M, Frank T, Zapf C, Mutters R, von Garrel T, “Lavage of Contaminated Surfaces: An In Vitro
Evaluation of the Effectiveness of Different Systems,” Journal of Surgical Research, V112. 2003.
25
Tomaselli F, Maier A, Renner H, Smolle-Juttner FM, “Thoracoscopic Water Jet Lavage in Coagulated
Hemothorax,” European Journal of Cardio-thoracic Surgery, V23. 2003.
26
Roby K, “My Canister Runneth Over,” Today’s Surgical Nurse, March/April 1999.
27
Trepman E, Denham J, “Containment Bag for Jet Irrigation of the Foot and Ankle,” Foot and Ankle International,
V21:1. 2000.
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literature was surveyed for studies of the frequency of blood contamination of the operating
room medical staff.
Quebbeman et al.28 performed a study that found most cases of blood exposure to be caused by
finger pricks with needles. For orthopedic surgeries, they found that 20% of all contaminations
occurred on the face, mostly from splattering of blood from power tools. They also note that for
orthopedic surgeries, “this group also had high rates of contamination of legs and feet due to the
blood running down the side of the operating table.” Lynch and White29,30 found that of 8502
surgeries investigated, 864 (10%) involved blood exposure to the skin of operating room staff.
They also observed that surgical team members often had bodily fluid run under the drapes and
onto their legs and feet. Fry et al.31 warn that operations involving power saws, drills, or
irrigation fluid pose a risk of splattering from blood or irrigation fluid. Jagger et al.32 studied
blood exposure to operating room staff and determined that blood splash, spray and spill is a
common occurrence in the operating room. They observed that, “it is not unusual in the
operating room environment for personnel to be exposed to blood even when they are located at
a significant distance from the patient.” It should be noted that these five studies were all
performed in 1990s, and common practices may have changed. A 2008 study by Meyers et al.33
examined 60,583 surgical procedures and found that 389 involved blood and fluid exposure by
means of needle-stick, contact with non-intact skin or mucous membrane, and one instance of
biting. These exposures represent a small fraction (0.64%) of all surgeries surveyed and
frequently do not involve significant amounts of blood.
28
Quebbeman EJ, Telford GL, Hubbard S, Wadsworth K, Hardman B, Goodman H, Gottlieb MK, “Risk of Blood
Contamination and Injury to Operating Room Personnel,” Annals of Surgery, V214:5. November 1991.
29
Lynch P, White MC, “Perioperative Blood Contact and Exposures: A comparison of Incident Reports and
Focused Studies,” American Journal of Infection Control, V21:357-363. 1993.
30
White MC, Lynch P, “Blood Contact and Exposures Among Operating Room Personnel: A Multicenter Study,”
American Journal of Infection Control, V21:243-248. 1993.
31
Fry DE, Telford GL, Fecteau DL, Sperling RS, Meyer AA, “Prevention of Blood Exposure, Prevention of
Transmission of Bloodborne Pathogens,” V75:6. December 1995.
32
Jagger J, Bentley M, Tereskerz P, “A Study of Patterns and Prevention of Blood Exposures in OR Personnel,”
Association of Perioperative Registered Nurses Journal, V67:5. May 1998.
33
Meyers DJ, Epling C, Dement J, Hunt D, “Risk of Sharp Device-Related Blood and Body Fluid Exposure in
Operating Rooms,” Infection Control and Hospital Epidemiology, V29:12. December 2008.
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2.1.1.4
Evidence of Blood and Fluid Spray and Splatter
Medical literature was surveyed for studies on blood and fluid spray and splash frequency during
surgical operations. These studies were conducted by examining the eye shields, glasses, and
gowns of operating room staff following surgeries and recording the presence of blood droplets.
For the purpose of these studies, contact with skin or mucous membrane is not necessary for the
splash to be counted. The results of the literature search are shown in Table 5.
Table 5. Observed Frequency of Blood Splash during Operating Room Surgical Procedures
Splash
Frequency (%)
Type of Surgery
Authors
Location
65
Orthopedic Surgery
Bell and Clement, 199134
UK
100
Bone cutting,
intramedulliary
reaming
Duthie et al., 199835
UK
62
C-Sections
Aisian et al., 200636
51
Vascular procedures
Berrige et al., 199337
UK
33
Dermatological
surgery
Birnie et al., 200738
UK
86
Orthopedic surgery
Collins et al., 200039
USA
50
32
C-Sections
40
USA
40
USA
Kouri et al., 1993
Vaginal births
Kouri et al., 1993
41
85
Surgical practitioners
Chong et al., 2007
NZ
26
General
Davies et al., 200742
UK
34
Bell KM, Clement DA, “Eye Protection for the Surgeon,” Journal of the Royal College of Surgeons, Edinburgh,
V36:179-179. 1991.
35
Duthie GS, Johnson SR, Packer GJ, Mackie IG, “Eye Protection, HIV, and Orthopedic Surgery,” The Lancet, pg
481-482. 1998.
36
Asian AO, Ujah IA, “Risk of Blood Splashes to Masks and Goggles during Caesarean Section,” Medical Science
Monitor, V12:94-97. 2006.
37
Berrige DC, Lees TA, Chamberlain J, Jones NA, “Eye Protection for the Vascular Surgeons,” British Journal of
Surgery, V80:1379-1380. 1993.
38
Birnie AJ, Thomas KS, Varma S, “Should Eye Protection be Worn During Dermatological Surgery: Prospective
Observational Study,” British Journal of Dermatology, V156. 2007.
39
Collins D, Rice J, Nicholson P, Barry K, “Quantification of Facial Contamination with Blood During Orthopaedic
Procedures,” Journal of Hospital Infection, V45:73-75. 2000.
40
Kouri DL, Ernest JM, “Incidence of Perceived and Actual Face Shield Contamination during Vaginal and
Caesarial Delivery,” American Journal of Obstetrics and Gynecology, V169:312-316. 1993.
41
Chong SJ, Smith C, Bialostocki A, McEwan CN, “Do Modern Spectacles Endanger Surgeons,” Annals of
Surgery, V245:3. March 2007.
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81
30
Vascular
Breast
Davies et al., 200742
UK
Davies et al., 2007
42
UK
15
UK
6
Colorectal
Davies et al., 2007
12
Endocrine
Davies et al., 200742
UK
9
Laproscopic
Davies et al., 200742
UK
45
Overall
Davies et al., 200742
45
UK
43
Overall
De Silva et al., 2009
44
Cape Town
51
Overall
Endo et al., 2007
Japan
75
Cardiovascular
Endo et al., 200744
Japan
69
Neurosurgery
Endo et al., 200744
Japan
Endo et al., 2007
44
Japan
Endo et al., 2007
44
Japan
60
60
Gastrointestinal
Orthopaedic Surgery
45
61
Tonsillectomy
Hanna et al., 2006
UK
66
Procedural
dermatology
Holzmann et al., 200846
US
60
Gynecological
surgeries
Sharma et al., 200347
India
49
Endourology
(urology)
Wines et al., 200848
UK
84
Laproscopic
nephrectomies
Wines et al., 200848
UK
68
Pyelplasties
Wines et al., 200848
UK
58
Flexible
ureteroscopies
Wines et al., 200848
UK
42
Davies CG, Khan MN, Ghauri A, Ranaboldo CJ, “Blood and Body Fluid Splashes During Surgery – The Need for
Eye Protection and Masks,” Annals of the Royal College of Surgeons of England, V89:770-772. 2007.
43
De Silva R, Mall A, Panieri E, Stupart D, Kahn D, “Risk of Blood Splashes to the Eye During Surgery,” South
African Journal of Surgery, V47:1. February 2009.
44
Endo S, Kanemitsu K, Ishii H, Narita M, Nemoto T, Yaginuma G, Mikami Y, Unno M, Hen R, Tabayashi K,
Matsushima T, Kunishima H, Kaku M, “Risk of Facial Splash in Four Major Surgical Specialties in a
Multicentre Study,” Journal of Hospital Infection Control, V67:56-61. 2007.
45
Hanna BC, Thompson P, Smyth C, Gallagher G, “Blood Splash from Different Diathermy Instruments During
Tonsillectomy,” The Journal of Laryngology and Otology, V120:927-931. 2006.
46
Holzmann RD, Liang M, Nadiminti H, McCarthy J, Gharia M, Jones J, Neel V, Schanbacher CF, “Blood
Exposure Risk During Procedural Dermatology,” Journal of the American Academy of Dermatologists, V58:5.
May 2008.
47
Sharma JB, Gupta A, Malhotra M, Arora R, “Facial and Body Blood Contamination in Major Gynecologic
Surgeries,” Journal of Obstetrics and Gynaecology Research, V29:6. December 2003.
48
Wines MP, Lamb A, Argyropoulos A, Caviezel A, Gannicliffe C, Tolley D, “Blood Splash Injury: A
Underestimated Risk in Endourology,” Journal of Endurology, V22:6. 2008.
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2.1.2 Evidence of Fluid on the Floor during Surgical Operations
Some data is available on the frequency of fluid spills on the floor of an operating room. In one
study, 5% of staff reported operating room procedures had pooling or ponding of fluids on the
floor.49 While some operating rooms have floor drains, others employ drainage containers to
collect fluids.50 If the level in these containers is not monitored, liquid can overflow and spill
onto the floor. During some surgical operations, significant spills of blood and irrigation fluid
can occur.51 Researchers estimate that the feet of surgeons become contaminated with blood in
13% of all operations, and with even greater frequency during higher blood loss procedures.52
2.2 Study of the Volume of Surgery in the United States
2.2.1 Introduction
The National Inpatient Sample (NIS) database is part of the Healthcare Cost and Utilization
Project (HCUP)53, sponsored by the Agency for Healthcare Research and Quality (AHRQ). The
NIS is the largest inpatient care database that is publicly available in the United States (US),
containing data from 5 to 8 million hospital stays from approximately 1,000 hospitals sampled to
approximate a 20% stratified sample of discharges from US community hospitals. Included
among community hospitals are specialty hospitals, such as obstetrics-gynecology, ear-nosethroat, short-term rehabilitation, orthopedic, and pediatric institutions, as well as public hospitals
and academic medical centers. Starting in 2005, the American Hospital Association (AHA)
included long term acute care facilities in the definition of community hospitals; therefore, such
facilities are included in the NIS sampling frame. Excluded from the NIS are short-term
rehabilitation hospitals (beginning with 1998 data), long term non-acute care hospitals,
psychiatric hospitals, and alcoholism/chemical dependency treatment facilities.
49
Kaiser Permanente NFPA 99 ROC, 2008.
Fortunato Nancymarie, ed. Berry and Kohn’s Operation Room Technique, Ninth edition, Mosby Missouri, USA,
2000.
51
Duensing RA, Mueller GP, Williams RA, “Hazards in the Operation Room,” Chapter 15: in Malangoni Mark A,
ed. Critical Issues in Operating Room Management, Lippencott Raven, Philadephia, PA USA, 1997.
52
Quebbeman EJ, Telford GL, Hubbard S, Wadsworth K, Hardman B, Goodman H, Gottlieb MS, “Risk of blood
contamination and injury to operating room personnel,” Ann Surg, V214:614-620. 1991.
53
Details about the NIS database and the HCUP program can be found at: http://www.hcupus.ahrq.gov/nisoverview.jsp
50
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NIS is the only national hospital database capturing information from all hospitalized patients,
regardless of payer, including persons covered by Medicare, Medicaid, private insurance, and the
uninsured. In 2008, NIS derived its data from discharge records from 1,056 hospitals located in
42 states (which comprise 95% of the US population). Sampling weights are provided by HCUP
to calculate national estimates. NIS data is available annually, dating back to 1988, allowing
analysis of trends over time. The large sample size of the NIS program enables analyses of rare
conditions, uncommon treatments, and hospital care associated with special patient populations,
such as the uninsured. Inpatient stay records in the NIS include clinical (e.g., diagnosis and
procedures) and resource use (e.g., hospital charges, length of stay) information typically
available from discharge abstracts. NIS can be linked directly to hospital-level data from the
AHA Annual Survey Database54 and to county-level data from the Health Resources and
Services Administration Bureau of Health Professions Area Resource File (ARF), except in
those states that do not allow the release of hospital identifiers.
2.2.2 Classification of Surgery
For each discharge record in the NIS, up to 15 procedures performed during the patient’s hospital
stay are recorded. It is often the case that more than one procedure was performed during a
patient’s stay. Thus, in the present tabulation, each procedure within a discharge record is
counted individually and used the same sampling weight for national projection. Procedures
within the ICD-9-CM system are grouped broadly by body-system categories (e.g., respiratory
system, digestive system) to facilitate summarization and tabulation. The same categories were
used in the present exercise. These broad groupings are shown in Table 6.
54
Health Forum, LLC © 2009
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Table 6. Surgical Groups by ICD-9-CM Codes
General Operation Type
ICD-9-CM Codes*
Nervous System
01 - 05
Endocrine System
06 - 07
Eye
08 - 16
Ear
18 - 20
Nose, Mouth, Pharynx
21 - 29
Respiratory System
30 - 34
Cardiovascular System
00.4 (adjunct vascular system
procedures), 00.5 (other
cardiovascular procedures) , 00.6
(blood vessels), 35 - 39
Hemic and Lymphatic
System
40 - 41
Digestive System
42 - 54
Urinary System
55 - 59
Male Genital Organs
60 - 64
Female Genital Organs
65 - 71
Obstetrical Procedures
72 - 75
Musculoskeletal (Orthopedic)
00.7 (hip), 00.8 (knee and hip), 76 84
Integumentary System (skin)
85 - 86
* These ICD-9-CM codes include all sub category numbers (e.g., code “08”
includes 08.1, 08.2, etc.)
2.2.3 Volume of Procedures by Surgical Category
Exponent used the NIS data from 2004 to 2008 for the present study. Table 7 provides the
estimated number of procedures performed each year in the US by the surgical categories listed
in Table 6. The surgical category “other” captures all other procedures not specifically
identified. These procedures primarily fall into the “diagnostic and therapeutic” category of
operations (e.g., radiology, ultrasound, cardiac stress tests) and many are considered “nonoperational.” Table 8 provides the estimated percentage of the total procedures performed each
year in the US by surgical category; these percentages exclude the “other” procedures in the
total, because these procedures do not necessarily occur in an operating room.
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Table 7. Procedure Volume by Surgical Category
2004
18,724,723
Other
1,585,832
Nervous
119,277
Endocrine
84,728
Eyes
40,548
Ear
318,548
Nose, Mouth, Pharnyx
1,383,407
Respiratory
9,053,227
Cardiovascular
419,794
Lymphatic
6,493,219
Digestive
1,155,112
Urinary
1,430,375
Genital Organ (M)
2,072,939
Genital Organ (F)
8,204,336
Obstetrical
4,510,191
Musculoskeletal
1,604,156
Integumentary
57,200,413
Total
2005
19,112,759
1,600,724
123,843
91,688
54,317
340,760
1,500,768
9,671,416
453,690
6,426,227
1,143,079
1,454,294
2,033,611
8,031,667
4,701,570
1,666,106
58,406,521
2006
19,644,035
1,527,188
120,031
75,152
40,098
305,862
1,473,182
11,876,237
425,866
6,339,841
1,182,217
1,442,856
1,943,275
8,198,686
4,865,166
1,611,333
61,071,026
2007
21,541,455
1,571,825
123,824
62,681
40,032
308,553
1,540,787
11,002,419
481,861
6,355,999
1,227,371
1,533,926
1,917,398
9,140,282
5,072,891
1,614,330
63,535,634
2008
21,404,916
1,615,942
139,947
66,124
43,096
305,676
1,594,918
11,518,844
490,140
6,687,489
1,334,942
1,463,496
1,812,658
8,233,054
5,592,545
1,619,323
63,923,111
Total
100,427,889
7,901,512
626,923
380,374
218,092
1,579,399
7,493,062
53,122,143
2,271,352
32,302,775
6,042,721
7,324,947
9,779,880
41,808,025
24,742,364
8,115,248
304,136,704
Table 8. Procedure Percentage of Total Volume by Surgical Category*
2004
2005
2006
2007
2008
Total
Nervous
4.1%
4.1%
3.7%
3.7%
3.8%
3.9%
Endocrine
0.3%
0.3%
0.3%
0.3%
0.3%
0.3%
Eyes
0.2%
0.2%
0.2%
0.1%
0.2%
0.2%
Ear
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
Nose, Mouth, Pharnyx
0.8%
0.9%
0.7%
0.7%
0.7%
0.8%
Respiratory
3.6%
3.8%
3.6%
3.7%
3.8%
3.7%
Cardiovascular
23.5%
24.6%
28.7%
26.2%
27.1%
26.1%
Lymphatic
1.1%
1.2%
1.0%
1.1%
1.2%
1.1%
Digestive
16.9%
16.4%
15.3%
15.1%
15.7%
15.9%
Urinary
3.0%
2.9%
2.9%
2.9%
3.1%
3.0%
Genital Organ (M)
3.7%
3.7%
3.5%
3.7%
3.4%
3.6%
Genital Organ (F)
5.4%
5.2%
4.7%
4.6%
4.3%
4.8%
Obstetrical
21.3%
20.4%
19.8%
21.8%
19.4%
20.5%
Musculoskeletal
11.7%
12.0%
11.7%
12.1%
13.2%
12.1%
Integumentary
4.2%
4.2%
3.9%
3.8%
3.8%
4.0%
100%
100%
100%
100%
100%
100%
Total
* The procedure percentages do not include the volume of the “Other” procedure category in the total
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2.3 Electrical Safety in the Operating Room
In the previous section, hospital operating room usage was evaluated to establish factors that
may lead to a wet or dry environment. In this section, the electrical hazards associated with
hospital operating rooms and safety practices cited in the literature are reviewed. Advantages
and disadvantages of the electrical power systems currently recommended by the NEC and
NFPA 99 for use in wet procedure locations and dry locations are summarized. A summary of
the design practices and policies establishing electrical classification of the operating room
environment in domestic and international settings is provided.
2.3.1 Electrical Hazards - Macroshock and Microshock
2.3.1.1
Macroshock
Macroshock is characterized as electric shock by greater than 5-1000 mA. Typically, current
passes through extremities or limbs of the human body.55 Dry human skin is characterized with
a resistance as great as 100,000 Ohms. Wet skin is characterized with a resistance on the order
of 1000 Ohms. The reduction in resistance of conducting electrical current exposes a person
with wet skin to risk of ventricular fibrillation from household voltages.56 This resistance to
current can also be lowered by perspiration, skin abrasion, surgical incision, external pacemaker
leads, and catheters that bypass the skin’s resistance. Patients who have an external conductor to
the heart, such as pacemaker leads, are “electrically susceptible” and can be affected by
microshock.56
55
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25, in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
56
Fung Dennis L, “Electrical Hazards,” Chapter 23, in Sosis Mitchel B, ed. Anesthesia Equipment Manual,
Lippencott-Raven, Philadelphia, PA, 1997.
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2.3.1.2
Microshock
Microshock is characterized as electric shock by currents as low as 10-180 µA, concentrated in
an area causing ventricular fibrillation, which is a severely abnormal heart rhythm.57,58
Microshocks occur below the threshold of perception, which is approximately 1 mA.58
Microshock currents can be attributed to one of three sources: 1) a cardiac lead as a current
source (e.g., where current is transferred to the catheters when using ungrounded devices); 2) a
cardiac lead as a current sink (e.g., where line current leaks from electrocardiograph to
pacemaker leads); and 3) a ground loop (e.g., where a patient is connected to two grounded
devices, one through a pacemaker lead, and then a third device not connected to the patient
which has a fault, but connected to the same power outlet circuit, which sends a high leakage
current through the ground connection, subsequently creating a resistance between the two
instrument grounds, and consequently sending a lethal leakage to the patient’s catheter).59
Electric shock could be caused by a difference in potential along the neutral lead, because all
conductors have some resistance, which makes stray capacitive or inductive currents possible.
Grounded electrodes attached to more than one part of the patient and from more than one piece
of equipment supplied by different outlets also facilitate stray capacitive or inductive currents.57
The two dominant mechanisms for leakage currents are capacitance associated with alternating
current power systems and voltage division occurring by either the built-in design of a medical
device or due to accidental insulation failure.60 Leakage current can also be attributed to
imperfect insulation between the load and surrounding metal work, which creates an alternative
pathway for current to return to the neutral line and stray or deliberate capacitance between live
circuits, such as transformers and ground.59
57
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25, in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
58
Ehrenwerth Jan, Seifert Harry A, “Electrical and Fire Safety,” in Barash Paul G, Cullen Bruce F, Stoelting Robert
K, eds. Clinical Anesthesia, 5th edition. Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
59
Hull CJ, “Electrocution Hazards in the Operating Theatre,” Br. J. Anaesth. V50:647-657. 1978.
60
Bruner John, “Hazards of Electrical Apparatus,” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
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Medical devices are required to have a ground current less than 100 µA.61 10 µA is the
maximum current leakage allowable through electrodes or catheters contacting the heart.62 In the
United Kingdom, all electrical equipment in the vicinity of the patient must conform to a leakage
specification of less than 10 µA under normal working conditions.63 Wherever possible, such
equipment should be battery operated and fully isolated from ground, however, all electrical
circuits making contact with the patient must be electrically isolated from ground; all equipment
susceptible to ground should be insulated.63 It is recommended that when using a grounded
system, the ground connections on all outlets in a single clinical area be interconnected by a low
resistance conductor to minimize voltage differences.64
2.3.2 Electrical Safety Standard Origins
The origin for improving electrical safety in hospital operating rooms began with efforts to
reduce the hazards associated with using flammable anesthesia. The focus of improving
electrical safety practices was on the reduction of sources of static electricity and electric shock
to improve fire safety. NFPA developed the first guideline on this topic in 1944, Safe Practices
in Hospital Operating Rooms. In 1947, the NFPA guideline was generally adopted and in 1948
isolated power systems (IPS) with line isolation monitors (LIMs) were implemented in all
anesthetizing locations. In 1949, the predecessor to NFPA 99 was codified.65
Despite the focus on electrical safety in operating rooms to ultimately improve fire safety, a lack
of standardization in wiring practices in operating rooms created electrical hazards. Specific
hazards are cited in the literature, for example, the use of external ground wires in parallel to
two-wire cords to ground medical equipment.66 In addition, it has been documented that 20% of
61
Fung Dennis L, “Electrical Hazards” Chapter 23 in Sosis Mitchel B, ed. Anesthesia Equipment Manual,
Lippencott-Raven, Philadelphia, PA, 1997.
62
Litt Lawrence, “Electrical Safety in the Operating Room,” Chapter 87 in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
63
Magee Patrick, Tooley Mark, The Physics, Clinical Measurement, and Equipment of Anaesthetic Practice, Oxford
University Press Inc., New York, USA, 2005.
64
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
65
Steven Engineering Inc. “Hospital Isolated Power Systems,” Catalog 4800CT9801R4/08, D Square D equipment
by Schneider Electric, 2008.
66
Bruner John, “Hazards of Electrical Apparatus,” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
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the electrical outlets in operating rooms in a hospital had improper socket wiring of the lead and
neutral conductors, because of an absence of wiring practice requirements in the local building
code.67
Electrocautery/electrosurgical unit devices were (and continue to be) a source of electrical
incidents attributed to improper use of medical devices, especially related to the placement and
contact of the associated grounding pad with the patient.68 User error and improper use of
medical devices are two of the most often cited reasons for patient injury by the Food and Drug
Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database.69
In the early 1960s, there was an increased focus on the prevalence of microshock in the medical
industry. In 1967 a journal article reviewing the hazards of electrical apparatus in the medical
industry, including the cause of at least 11 incidents of shock and ventricular fibrillation that
occurred during surgical procedures from 1960 to 1967, was published.70 The author concluded
that electric shock by medical devices is not rare, and improved electrical safety requires
equipment to be properly grounded.
More recent reviews of medical literature71,72 allege that unsubstantiated statistics were
circulated in the medical industry, stating 1,200 incidents per year were due to misdiagnosed
microshock electrocutions.73 Subsequently, these statistics were repeated and extrapolated
67
Atkin David H, Orkin Louis R, "Electrocution in the operating room," Anesthesiology, V38:2:181-183, Feb. 1973.
68
Duensing Robert A, Mueller Gregory P, Williams Russell A, “Hazards in the Operation Room,” Chapter 15 in
Malangoni Mark A, ed. Critical Issues in Operating Room Management, Lippencott Raven, Philadephia, PA
USA, 1997.
69
Epstein Alice L, Harding Gary H, “Risk Management,” in Dyro Joseph F, ed. Clinical Engineering Handbook,
Elsevier Inc, Burlington MA, 2004.
70
Bruner John, “Hazards of Electrical Apparatus” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
71
Square D, “Isolated Power Systems (IPS) and Wet Locations in Healthcare Facilities,” Technical White Paper #
0104DB701, Schneider Electric, Palatine, IL, December 2007. Accessed September 2010. static.schneiderelectric.us/docs/electrical%20Distribution/0104DB0701.pdf
72
Bruner John MR, Leonard Paul F, Electricity Safety and the Patient, Year Book Medical Publishers, Chicago, Ill,
1989.
73
Walter Carl, “Electrical Hazards in Hospitals” in proceedings of the 1968 workshop sponsored by the National
Research Council, ed. Walter, Carl W, National Academy of Sciences, 1970.
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without justification to 5,000 incidents per year.74 The medical literature reviews71,72 indicate
that these claims were the driving force for the NFPA Committee on Hospitals to advocate and
implement requirements for the use of IPS as a safeguard against microshock.
2.3.3 Electrical Safety Practices
Throughout the literature reviewed, a number of electrical safety practices for the operating room
are recommended. Electrical cords that extend down walls or those that cross the floor are
considered hazardous, because they create a tripping hazard.75 Power cables should not be
stretched across traffic lanes.75 Straight or curved ceiling mounted tracks and articulating booms
should be used to bring electrical outlets close to the operating room table.75 Multiple-plug
extension boxes (i.e. power taps) should not be left on the floor where they can come in contact
with fluids and electrolyte solutions.76 When power taps are employed in the operating room,
outlets should include watertight covers that flip into place when unused.77 Extension cords with
power taps should not be used in operating rooms, because they are a tripping hazard and, “any
saline-based (therefore conductive) irrigation that ends up on the floor can soak the sockets and
allow electricity to flow from the extension via the shortest route to earth.”78
A number of additional safeguards to electrical shock are recommened.75 Liquids should not be
placed on an electrical device. Machines should be turned off when plugging in cords to power
outlets. Electrosurgical and laser units may interfere with operation of other equipment,
therefore, these units should be located on the operators’ side of the table and far from
monitoring equipment. Additionally, the units should be plugged into separate circuits, with no
extension cords. Care should be taken when operating any electrical equipment. The units
should be regularly checked for frayed or broken power cords, functioning power switches, and
74
In June 1970, a report was distributed by the UPI wire service that Ralph Nader alleged in a speech that 5000
deaths attributed to microshock occurred each year in the nation's hospitals.
75
Fortunato Nancymarie, ed., Berry and Kohn’s Operation Room Technique, 9th edition, Mosby, Missouri, USA,
2000.
76
Ehrenwerth Jan, Seifert Harry A, “Electrical and Fire Safety” in Barash Paul G, Cullen Bruce F, Stoelting Robert
K, eds. Clinical Anesthesia, 5th edition. Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
77
Litt Lawrence, “Electrical Safety in the Operating Room,” Chapter 87, in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
78
Graham Stephen, “Electrical safety in the operating theatre,” Current Anaesthesia & Critical Care, V15:350-354.
2004.
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proper grounding. All electrical equipment should be inspected by the biomedical engineering
department before initial use and routinely, preferably monthly, but at least quarterly.79
In addition to general electrical safety, there are several safety recommendations in the literature
for working around electrically sensitive patients. When pacemaker leads or catheters are
handled, gloves should be used.80 Additionally, a pacemaker lead or catheter should not be
handled while also in contact with an oscilloscope, monitor, or other electrically powered
equipment.81
2.3.4 Electrical Power Systems in the US Medical Industry
2.3.4.1
Grounded Systems
Grounded power systems are used when a location is not classified as a wet procedure location.
In this system there is a common ground. There is a high current threshold at the circuit breaker
for interrupting power in the event of an electrical short or fault condition to a low impedance
pathway. Connecting a low impedance pathway from the hot conductor at 120 VAC to the
ground conductor will allow heavy current to flow. If this current passes through a person, a
macroshock can occur.82 Typically, a grounded power system has a lower cost of installation
and maintenance in comparison to an IPS with LIMs.83,84,85,86
79
Fortunato Nancymarie, ed. Berry and Kohn’s Operation Room Technique, 9th edition, Mosby, Missouri, USA,
2000.
80
Ehrenwerth Jan, Seifert Harry A, “Electrical and Fire Safety” in Barash Paul G, Cullen Bruce F, Stoelting Robert
K, eds. Clinical Anesthesia, 5th edition. Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
81
Magee Patrick, Tooley Mark, The Physics, Clinical Measurement, and Equipment of Anaesthetic Practice, Oxford
University Press Inc., New York, USA, 2005.
82
Baretich Matthew F, “The Isolated Power Systems Debate,” 24x7 Magazine, December 2007. Accessed
September 2010, www.24x7mag.com/issues/articles/2007-12_03.asp.
83
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
84
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words,” 2004 AIA/ASHE International Conference
on Planning, Design & Construction, March 2004.
85
Hull CJ, “Electrocution Hazards in the Operating Theatre,” Br. J. Anaesth. V50:647-657. 1978.
86
Litt Lawrence, “Electrical Safety in the Operating Room,” Chapter 87, in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
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In the event of a short circuit in an electrical device that has a three-prong plug, where the
ground wire is connected to the chassis of the unit, the ground wire will conduct the majority of
the fault current away from the person in contact with the unit.87 Electronic devices without a
ground wire should not be used in the operating room, as a person touching a medical device
chassis with a ground fault will receive a shock.87
2.3.4.2
IPS
IPSs are used when a location is classified as a wet procedure location. This type of system
significantly reduces the potential for macroshock to occur. The voltage from either of the two
line conductors (analogous to the hot and neutral of a ground-based system) is approximately 60
VAC, and connecting a low impedance pathway from either of the lines to ground will produce
some current flow, typically on the order of a few mA, depending on the level of isolation.88 The
LIM detects degraded isolation of the system, which creates a potential low impedance pathway
to ground and provides alarm notification.88,89 If a fault occurs, the power is not automatically
tripped to other devices on the same circuit, instead, an alarm will sound by the LIM to notify
personnel to investigate the alarm source.
An IPS may supply power to the entire operating room90, however, a hospital can elect to power
equipment directly involved with the surgical operations and required to maintain life support
with an IPS, and implement a conventional grounded power system for lighting circuits and
equipment not required to maintain life support.
87
Ehrenwerth Jan, Seifert Harry A, “Electrical and Fire Safety” in Barash Paul G, Cullen Bruce F, Stoelting Robert
K, eds. Clinical Anesthesia, 5th edition. Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
88
Baretich Matthew F, “The Isolated Power Systems Debate,” 24x7 Magazine, December 2007. Accessed
September 2010, www.24x7mag.com/issues/articles/2007-12_03.asp.
89
Bruner John, “Hazards of Electrical Apparatus” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
90
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
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An IPS does not prevent microshock, because currents of 2 to 5 mA potentially flow undetected,
below the threshold of the LIM.91,92,93 The allowable leakage current alarm level of the LIM is
currently 5 mA.97
The sum of several appliances in use on an individual circuit, each having degraded isolation
with a small leakage current potential can trip the LIM alarm.94,95 Frequent LIM alarms due to
multiple devices and/or aging wiring can lead to desensitization of “nuisance alarms”, causing
personnel to ignore the LIM.96,97 In 1981, the allowable leakage current permitted by the NEC
and NFPA 99 was increased from 2 mA to 5 mA to reduce nuisance alarms.97 Another
disadvantage of the LIM is that it is susceptible to newly developed artifactual causes of alarm
(e.g., devices that emit electrical radiation, such as instruments that generate ultrasonic sound
waves for tumor disintegration and aspiration and stereotaxic monitors that use radio waves to
track sensors attached to patients).92 If a LIM alarm is ignored, a hazard could occur if a second
fault is present in which the other supply wire is grounded.98
The safety of an isolated circuit can be defeated by an unrecognized unintentional connection to
ground (i.e. a defective device with an internal fault to the grounded chassis).99,100
Manufacturers of electrical equipment often place separate isolation transformers within the
91
Bruner John, “Hazards of Electrical Apparatus” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
92
Litt Lawrence, “Electrical Safety in the Operating Room,” Chapter 87, in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
93
Hull CJ, “Electrocution Hazards in the Operating Theatre,” Br. J. Anaesth. V50:647-657. 1978.
94
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
95
Baretich Matthew F, “The Isolated Power Systems Debate,” 24x7 Magazine, December 2007. Accessed
September 2010, www.24x7mag.com/issues/articles/2007-12_03.asp.
96
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words,” 2004 AIA/ASHE International Conference
on Planning, Design & Construction, March 2004.
97
D Square D, “Isolated Power Systems (IPS) and Wet Locations in Healthcare Facilities,” technical white paper
#0104DB0701, Schneider Electric, Palatine, IL, December 2007. accessed September 2010,
ecatalog.squared.com/pubs/Electrical%20Distribution/0104DB0701.pdf
98
Courtney NM, McCoy EP, Scolaro RJ, Watt PA, “A Serious and Repeatable Electrical Hazard – Compressed
Electrical Cord and an Operating Table,” Anaesthesia & Intensive Care, V34:3:392-396, 2006.
99
Fung Dennis L, “Electrical Hazards,” Chapter 23 in Mitchel B. ed. Anesthesia Equipment Manual, LippencottRaven, Philadelphia, PA, 1997.
100
Gilbert Timothy B, Shaffer Michael, Matthews Marianne, “Electric Shock by Dislodged Spark Gap in Bipolar
Electrosurgical Device,” Anesthesia & Analgesia, V73:355-357, 1991.
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power supply of their products;95,97, causing the LIM to be insensitive to ground faults distal to
the second level of isolation.100
2.3.4.3
GFCIs
GFCIs are used on particular circuits in conjunction with a grounded power system, when an
area is classified as a wet procedure location. GFCI outlets eliminate the potential for
macroshock to occur.101 The GFCI circuit is designed to sense a specified difference or
imbalance in the current flow in the range of 4 to 6 mA between the hot conductor and either the
ground or the neutral conductor of the same circuit. This diversion of current is usually
associated with unintended leakage current or an unintentional low impedance pathway to
ground, such as human contact.102 When the current difference is sensed, the circuit is tripped in
milliseconds. The GFCI can be manually reset and is equipped with a test button.
A single fault trips the GFCI and disconnects the power to all devices on the circuit. Therefore,
it is widely recognized in the literature that GFCIs are not for use with life support or other
critical operation equipment. GFCIs also have similar problems to isolating transformers, when
the sum of several appliances in use on an individual circuit each has degraded isolation with a
small leakage current potential.103 GFCIs do not prevent microshock, because currents below 4
to 6 mA potentially flow without alarm or power shutoff.101
2.3.5 Electrical System Design Practices and Commentary in the Medical
Industry
In the current edition of NFPA 99, the governing body of the hospital facility is responsible for
designating their operating rooms as a critical care areas and classifying whether the areas are a
wet procedure location. A number of groups in the healthcare industry have made statements
and policies relating to environmental classification, including:
101
Hull CJ, “Electrocution Hazards in the Operating Theatre,” Br. J. Anaesth. V50:647-657. 1978.
102
D Square D, “Isolated Power Systems (IPS) and Wet Locations in Healthcare Facilities,” Technical White Paper
#0104DB0701, Schneider Electric, Palatine, IL, December 2007. accessed September 2010,
ecatalog.squared.com/pubs/Electrical%20Distribution/0104DB0701.pdf
103
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali, eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
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•
Governmental agencies;
•
Professional associations and societies;
•
Authorities having jurisdiction, including individual states; and
•
Other stakeholders, including hospital staff.
2.3.5.1
Governmental Agencies
Department of Defense (DOD) policy specifies (post 2002) that operating rooms, delivery
rooms, cystoscopy rooms, oral surgery, cardiac catheterization rooms and other such rooms are
not wet areas.104 The prior DOD policy (1991) classified operating rooms, delivery rooms,
hydrotherapy, and therapeutic pool areas as wet use areas corresponding to NFPA 99.105
The 2008 directive of the Veterans Health Administration (VHA) declares that operating rooms
and cardiac catheterization rooms are not wet locations for electrical safety purposes.106
Historically, these rooms within VHA facilities were designated as wet locations and required
IPSs. A previous (2002) VHA directive declared areas used for cystoscopy, arthroscopy, and
birthing rooms labor/delivery as wet areas.107
2.3.5.2
Professional Associations and Societies
The Emergency Care Research Institute (ECRI) maintains that hospital operating rooms are not
designated as wet locations.108 They have stated that investing in isolated power and
equipotential grounding systems are both unreasonable and unnecessary.109
104
Military Handbook, Department of Defense Medical Military Facilities Design and Construction Criteria, MILHDBK-1191, 2002 edition. Section 10.1.2.3.
105
Military Handbook, Department of Defense Medical and Dental Treatment Facilities Design and Construction
Criteria, MIL-HDBK-1191, 1991 edition. Section 4.8.2.2.
106
Department of Veterans Affairs, Veterans Health Administration, Electrical Safety Policy for Patient Care
Equipment, VHA Directive 2008-011, 2008.
107
Department of Veterans Affairs, Veterans Health Administration, Electrical Safety Policy for Patient Care
Equipment, VHA Directive 2002-030, 2002.
108
ECRI, “Electrical Safety Q&A. A Reference Guide for the Clinical Engineer.” Health Devices, V34:2:57-75,
2005.
109
ECRI, “Isolated Power and Equipotential Grounding Systems." Health Devices, V25:1:23-24, Jan. 1996.
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During the 2008 American Society for Healthcare Engineering (ASHE) 45th Annual Conference
and Technical Exhibition, 120 member participants unanimously voted to have ASHE oppose
that all operating rooms be considered wet locations.110
The American Society of Anesthesiologists (ASA) in 2008 approved a “Statement on Nonoperating Room Anesthetizing Locations”, which issued guidelines for any anesthetizing
location and provided examples of wet locations: cystoscopy, arthroscopy, birthing room in labor
and delivery.111
The Association for the Advancement of Medical Instrumentation (AAMI) 2004 Electrical
Safety Manual states that operating rooms are not necessarily wet locations. Currently, a 2008
document has been released with recommendations based on ANSI/AAMI ES60601-1 Medical
electrical equipment – Part 1: General requirements for basic safety and essential performance
and the latest editions of NFPA 72 and NFPA 99.112
The Institute of Electrical and Electronics Engineers (IEEE) publishes a recommended practice
for electrical systems in health care facilities, which summarizes the debate of opinions on
whether operating rooms should be considered wet or dry locations and refers to the current
edition of the NEC and NFPA 99 for guidance on the classification.113
The 2010 Hospital Accreditation Standards released by The Joint Commission on Accreditation
of Healthcare Organizations (JCAHO) refers to current applicable standards regarding the
classification of operating rooms as wet or dry environments.114
110
ASHE Regulatory Advisory, “Operating Rooms to be Considered Wet Locations: Your Support is Needed
Today,” accessed September 2010: http://www.ashe.org/advocacy/advisories/2008/wet080812.html
111
ASA “Statement on Non-operating Room Anesthetizing Locations” Standards and Practice Parameters
committee, amended October 22, 2008. Accessed September 2010,
www.asahq.org/publicationsAndServices/standards/14.pdf
112
Baretich Matthew F, Shepherd Marvin, “Electrical Safety Manual 2008: A Comprehensive Guide to Electrical
Safety Standards for Healthcare Facilities,” Association for the Advancement of Medical Instrumentation, 2008.
113
IEEE, “IEEE White Book, 602, IEEE Recommended Practice for Electric Systems in Health Care Facilities,”
IEEE Std 602-2007, 2007.
114
Joint Commission (JCAHO), “2010 Hospital Accreditation Standards” 2009.
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2.3.5.3
Individual State – Authority Having Jurisdiction
The authority having jurisdiction governing a health care facility has the ability to supersede the
minimal requirements of NFPA 99 with regard to requiring IPSs in operating rooms. Local and
state jurisdictions can have different requirements, and the governing bodies should be consulted.
2.3.5.4
Literature
In the literature, a number of stakeholders, including hospital groups and healthcare
professionals, have contributed opinions to the debate of whether operating rooms should be
classified as wet procedure locations or dry locations. The following citations are the result of a
literature review of publically available journal articles, healthcare studies, and health care
textbooks. The contributors typically speak from experience; however, there is limited
documentation of specific operating room procedures, surgeries, clinical studies, or incident
statistics.
Kaiser Permanente, a national health care provider undertook an empirical study of the
effectiveness of IPSs in comparison to grounded power systems in their hospital operating
rooms. In approximately 1992, Kaiser Permanente chose to discontinue installing IPSs in their
operating rooms.115 An assessment of the study data of safety records and interviews with
hospital staff revealed that electrical problems were rare in operating rooms with grounded
power systems, and that IPSs do not provide the promised benefit of improving electrical safety.
Kaiser Permanente also concluded that IPSs potentially have harmful side effects, specifically
nuisance alarms to LIM alarms and desensitization.115 Kaiser Permanente conducted another
survey of their hospitals with both grounded power systems and IPSs in response to the 2009
NFPA 99 public comment cycle.116 The study found no history of injury due to electric shock,
with rare instances of minor electrical shock. Kaiser Permanente determined that by spending
capital funds on IPSs, the opportunity is lost to upgrade operating rooms with new medical
equipment, wiring, and better maintenance procedures.116
115
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words” presentation at the 2004 AIA/ASHE
International Conference on Planning Design & Construction, Mazzetti & Associates. March 17, 2004.
116
Kaiser Permanente, comment submitted to NFPA 99-2009 ROC, 2008.
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Jan Ehrenwerth, a professor of anesthesiology at Yale University, John Wills and Dan Rogers,
both professors of anesthesiology and critical care medicine at the University of New Mexico,
describe an incident involving saline irrigation fluid from a cystoscopy procedure on the floor of
an operating room. Ehrenwerth et al. also allege that prior to the procedure, the operating room
had been cleaned by throwing buckets of water on the floor. The authors indicate that blood
spillage onto the floor occurs in many major surgical operations and irrigation fluid spillage onto
the floor during arthroscopies and cystoscopies frequently occurs. They conclude that operating
rooms should be designated as wet procedure locations.117
Steven Barker, a professor of anesthesiology from the University of Arizona, and D. John Doyle
a medical professor at Case Western Reserve University, describe that an operating room has an
almost universal presence of liquids, including water, blood, gastrointestinal contents, urine, etc.,
on the floor. They concede that there may be operating rooms that can usually be kept dry.
They conclude from their experience that operating rooms are never dry locations.118
Other literature review findings are as follows:
•
Dennis Fung, a professor of anesthesiology at the University of California, states that
operating rooms are wet environments and therefore electrically hazardous.119
•
Lawrence Litt, a professor of anesthesia and perioperative care at the University of
California in San Francisco, references common wet events in operating rooms as
dripping of saline, blood or other conducting liquid on the floor.120
•
Franklin Day, a doctor in the Department of Anesthesiology in the Oakland, California
Naval Hospital, indicates that while not all anesthetizing locations qualify as wet
procedure locations, general purpose operating rooms and obstetric delivery rooms
117
Wills John H, Ehrenwerth Jan, Rogers Dan, “Electrical Injury to a Nurse Due to Conductive Fluid in an
Operating Room Designated as a Dry Location,” Anesthesia & Analgesia, V110:6:1647-1649, 2010.
118
Barker Steven J, Doyle D John, “Electrical Safety in the Operating Room: Dry vs. Wet” Anesthesia & Analgesia,
V110:6:1517-1518, June 2010.
119
Fung Dennis, “Electrical Hazards,” Chapter 23 in Sosis Mitchel B. ed. Anesthesia Equipment Manual,
Lippencott-Raven, Philadelphia, PA, 1997.
120
Litt Lawrence, “Electrical Safety in the Operating Room,” Chapter 87 in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
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appear to meet the definition of a wet procedure location and should be designated as
such.121
•
Lawrence Litt and Jan Ehrenwerth further characterize numerous types of surgeries as a
wet environment122 and cite three other references that characterize operating rooms as
wet procedure locations.123
2.3.6 Comparable Foreign Electrical System Standards in the Medical
Industry
The comparable international electrical system standard to NFPA 99 is International
Electrotechnical Commission (IEC) 60364-7-710:2002, Electrical Installations of Buildings,
Requirements for Special Installations or Locations – Medical Locations. The standard does not
designate operating rooms as wet procedure locations, however, the standard requires hospital
operating rooms have Group 2 protection124, which requires IPSs (designated as isolating
transformers [IT]) for life support equipment.124 The LIM detection requirement is less than or
equal to 1 mA peak current under a fault condition.125 There are also power requirements for
non-life supporting equipment. Operating rooms with Group 2 protection require GFCIs (called
residual current devices [RCDs]) with 30 mA operating current on the following equipment:
circuits for the supply of operating tables (for mechanical controls), circuits for X-ray units,
circuits for large equipment with a rated power greater than 5 kVA, and circuits for non-critical
electrical equipment (non life-support).126 In addition, in Group 2 operating rooms where
121
Day Franklin J, “Electrical Safety Revisited: A New Wrinkle,” Anesthesiology, V80:1:220-221, 1994.
122
Litt Lawrence, Ehrenwerth Jan, “Electrical Safety in the Operating Room: Important Old Wine, Disguised New
Bottles,” Anesthesia & Analgesia, V78: 417-419. 1994.
123
Matjasko MJ, Ashman MN. “All you need to know about electrical safety in the operating room.” in Barash PG,
Deutsch S, Tinker J, eds. ASA refresher courses in anesthesiology. Vol. 18. Philadelphia: JB Lippincott, 1990;
Bruner JMR, Leonard PF, Electricity, safety and the patient. Chicago: Year Book Medical Publishers, pg 300,
1989; Lennon RL, Leonard PE, “A hitherto unreported virtue of the isolated power system [letter].” Anesthesia
& Analgesia, V66:1056-1057. 1987.
124
IEC 60364-7-710: 2002, section 710.3.7
125
IEC 60364-7-710: 2002, section 710.413.1.5
126
IEC 60364-7-710: 2002, section 710.413.1.3
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intracardiac procedures take place, supplementary equipotential bonding conductors are required
(connected to earth reference bar).127
In the United Kingdom, the comparable medical industry electrical system standard is Health
Technical Memorandum HTM 2007:1993 Electrical Services Supply and Distribution, which
has technical recommendations in-line with British Standard BS 7671 Requirements for
Electrical Installations, and IEE Guidance Note 7:2004, Special Locations, 2nd edition, Chapter
10 – Medical Locations, which is based on IEC 60364-7-710 requirements.
New Zealand and Australia follow AS/NZS 2500:2004, Guide to the safe use of electricity in
patient care, and AS/NZS 3003:2003, Electrical installations - patient treatment areas of
hospitals and medical, dental practices and dialyzing locations. The Australian and New
Zealand standards require that cardiac and body protected areas incorporate either GFCIs
(RCDs) or an IT and LIM (IPS with an LIM).128 For cardiac protected areas, both systems also
require a ground connection to any conductive object either directly or indirectly in contact with
the patient. This is to protect against microshock causing ventricular fibrillation induced by
small currents flowing to the heart via pace maker wires and pulmonary artery catheters.128
In Canada, the comparable medical industry electrical system standard is the Canadian Electric
Code: 2009. Rule 24-116 has requirements similar to NFPA 99, where IPSs are optional in
operating rooms and required in wet procedure locations. However, there is an exception in New
Brunswick, where regulations state that IPSs should not be installed.129 A document issued by
the Institute of Biomedical Engineering at the University of New Brunswick to supplement the
Canadian Electric Code states that isolated electrical systems are not effective in reducing the
hazard of microshock. The restrictions on electromedical equipment and other safety
precautions that are necessary to protect patients from microshock hazards serve also to protect
127
IEC 60364-7-710: 2002, section 710.413.1.6
128
Courtney NM, McCoy EP, Scolaro RJ, Watt PA, “A Serious and Repeatable Electrical Hazard – Compressed
Electrical Cord and an Operating Table,” Anaesthesia & Intensive Care, V34:3:392-396, 2006.
129
Easty Tony, NFPA comment for NFPA99-2009 on Isolated Power Systems. “Summary Report on the
Installation of Isolated Power in Critical Patient Treatment Areas at University Health Network,” 2008.
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against higher current shock and are effective with grounded, as well as isolated electrical
systems.130
2.3.7 Electrical Equipment Design Practices
In recent years, there has been an improvement in medical device regulation and more stringent
standards for the design of medical electrical equipment. The current international standard is
IEC 60601-1:2006, Medical electrical equipment - General requirements for basic safety and
essential performance. Other countries have adopted this standard, for example, the US has
adopted the standard with deviations, as well as Canada, Brazil, Japan, Korea, and Australia/New
Zealand. In the IEC 60601 code family there are collateral standards governing medical systems,
electromagnetic compatibility (EMC), radiation protection, and medical device software. There
are also standards for specific types of devices (e.g. electrosurgical equipment, hospital beds).
The underlying philosophy of IEC 60601-1 is that equipment must be safe in normal and single
fault conditions. The device design requires two layers of protection against excessive
unintentional current, defined as leakage current, passing through the patient or operator.131
Electric shock risk is reduced by either grounding the chassis or preventing the operator from
being able to touch the chassis.132 The design is also required to be evaluated to demonstrate that
it is safe in normal and single fault conditions.131
2.3.7.1
Medical Device Design as an Alternative Electrical Safety Practice
A number of citations in the literature recommend that medical device design can improve
electrical safety as an alternative to the electrical power system design. A better alternative to an
IPS with a LIM is to include a small isolating transformer in the circuitry of each individual item
of electrically powered medical equipment, which can be connected to the patient.133 The patient
130
Institute of Biomedical Engineering, University of New Brunswick, “Wiring Guidelines – for patient service
areas in New Brunswick Hospitals,” October 2006.
131
Biersach Brian R, Marcus Michael L, “Designing Medical Electrical Equipment to Meet Safety Certification and
Regulatory Requirements” Medical Equipment Compliance Associates, LLC, accessed August 2010,
www.mecaassociates.com/info_01.pdf
132
Graham Stephen, “Electrical safety in the operating theatre,” Current Anaesthesia & Critical Care, V15:350-354.
2004.
133
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali. eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
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circuit is not connected to ground (fully floating), but the equipment enclosure may be
earthed/grounded.134 Most electrical equipment used in an operating room already has built-in
electrical isolation of output power.135 The necessity of installation of IPSs and LIMs in
operating rooms is questioned, and it is concluded that the decision depends on the type of
electrical equipment that is used and on the surgical situation.135
The reliability of medical devices as an expectation of a clinical user’s needs is also discussed.
The authors describe the typical product life-cycle environment of a medical electronic device
through an example scenario, where an emergency room physician moves monitors around in the
emergency room, bumping them into stationary objects, dropping them on the floor, and
spraying them with liquids. The authors express the importance of defining the product lifecycle environment as a step in the suggested Design for Reliability Paradigm used by the authors
to reduce the ambiguity of the FDA direction for medical device design.136 FDA regulation
§860.7 (b) identifies four relevant factors that should be considered when assessing safety and
effectiveness, the second of which is “the conditions of use for the device, including conditions
of use prescribed, recommended, or suggested in the labeling or advertising of the device, and
other intended conditions of use.”
134
Magee Patrick T, “Electrical Hazards and their Prevention,” Chapter 25 in Davey Andrew J, Diba Ali. eds.
Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
135
Litt, Lawrence, “Electrical Safety in the Operating Room,” Chapter 87 in Miller Ronald D, ed. Miller’s
Anesthesia, 6th edition, Elsevier, Churchill, Livingstone, Philadelphia, PA, 2005.
136
Weininger Sandy, Pecht Michael, “Exploring Medical Device Reliability and Its Relationship to Safety and
Effectiveness,” IEEE, 2009.
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2.4 Incident Reporting of Electrical Related Injuries in an
Operating Room
In this section, criteria and classifications for reporting adverse events in the medical industry are
reviewed. A selection of databases of medical adverse event and incident reporting are reviewed
and summarized. Data relating to electrical incidents in hospital operating rooms or the general
health care industry are presented when available. In the literature, a number of trends in adverse
event reporting were identified that have effects on the electric shock incidence rate in hospital
operating rooms. The medical literature was searched for electric shock incidents occurring in
hospital operating rooms. Case studies summarizing electric shock events occurring in a hospital
operating room are organized by decade.137
2.4.1 Medical Incident Reporting
In the US, it is estimated that up to 99,000 hospitalized patients die annually due to medical
errors, in combination with errors of omission, hospital acquired infections, and adverse events
in nursing home and ambulatory care settings.138,139 In 1999, the Institute of Medicine (IOM)
called for a nationwide, mandatory reporting system of standardized information about adverse
events to be provided for state government collection.138 State governments are currently in the
process of forming, developing and refining their adverse reporting systems in response to this
IOM report.
There are a number of regulatory imperatives in the medical industry for reporting incidents and
adverse events:
•
The Safe Medical Devices Act (SMDA) requires that a hospital report any incident in
which the manufacturer’s medical device may have contributed to injury to the
137
It should be noted that some of the citations were only found through examination of the reference lists of other
relevant documents. Therefore, it should not be expected that the reviewed list of incidents in the published
literature is complete.
138
Rosenthal Jill, Takach Mary, “2007 Guide to State Adverse Event Reporting Systems,” State Health Policy
Survey Report, V1:1, Publication # 2007-301, National Academy for State Health Policy, Portland, ME, 2007.
139
National Quality Forum, “The Power of Safety: State Reporting Provides Lessons in Reducing Harm, Improving
Care,” National Quality Forum, Quality Connections, Washington DC, 2010.
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manufacturer within 10 business days. If the manufacturer is unknown, the occurrence
must be reported to the FDA.140
•
JCAHO requires hospitals have a mechanism to analyze and reduce sentinel events
through corrective action.140 Sentinel events are an unexpected occurrence involving
death or serious physical or psychological injury.
•
The Occupational Safety and Health Administration (OSHA) must be alerted when an
employee’s health has been compromised by an injury in the workplace.
•
Additionally, the state health department and local, regional, and national authorities have
reporting requirements for accidents that result in injuries.140
In the following sections, a selection of databases related to medical adverse event and incident
reporting are reviewed and summarized. Data relating to electrical incidents in hospital
operating rooms or the general health care industry are presented when available.
2.4.1.1
Groups Monitoring Medical Incident Databases
After the 1999 IOM report, the National Academy for State Health Policy (NASHP) tracked
state adverse event reporting systems that were formed with the intent to improve patient safety.
In 2007, NASHP issued a survey report summarizing the progress of state efforts to implement
adverse event reporting systems.141 The NASHP website also provides links to the adverse event
reporting tools by state, allowing access to publically available reports of the compiled state
findings.142
AHRQ also maintains a comprehensive list of event reporting systems, including state,
government, foreign government, independent, and health care agency reporting programs.143
AHRQ is in the process of developing a Network of Patient Safety Databases (NPSD) that will
receive, analyze and report on nationally aggregated patient safety event information. Currently,
140
Dyro Joseph F, “Accident Investigation” Chapter 64 in Dyro Joseph F, ed. Clinical Engineering Handbook,
Elsevier Inc, Burlington MA, 2004.
141
Rosenthal Jill, Takach Mary, “2007 Guide to State Adverse Event Reporting Systems,” State Health Policy
Survey Report, V1:1, Publication # 2007-301, National Academy for State Health Policy, Portland, ME, 2007.
142
http://www.nashp.org/pst-state-list
143
http://www.pso.ahrq.gov/formats/psersys.htm
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there is no centralized adverse event reporting system for hospitals to submit adverse event data,
which would disseminate adverse event information to a national audience. Instead, there are
separate federal, state and nongovernmental entities that receive and disclose adverse event
information. Depending on the entity, reporting by hospitals is either voluntary or mandatory,
and the entities have different data collection procedures, privacy protections, and dissemination
practices. AHRQ officials have estimated that initial NPSD data will be available for analysis
and disclosure in early 2011.144
AHRQ has also developed a reporting framework to assist hospitals with reporting complete
descriptions of event records145, including eight event-specific common formats pertaining to
frequently occurring and/or serious patient safety events:146
•
Blood or blood product;
•
Device or medical/surgical supply;
•
Fall;
•
Healthcare associated infection;
•
Medication or other substance;
•
Perinatal;
•
Pressure ulcer; and
•
Surgery or anesthesia.
None of the AHRQ common formats relate specifically to electric shock incidents.
The National Quality Forum (NQF), with support from the US Department of Health and Human
Services, also aims to improve the quality of healthcare in the US by monitoring state adverse
event reporting activities. In 2002, NQF published a report summarizing a consensus-based list
144
Wright S, “Memorandum Report: Adverse Events in Hospitals: Public Disclosure of Information about Events”
OEI-06-09-00360, Department of Health & Human Services, Washington DC, January 5, 2010.
145
http://www.pso.ahrq.gov/formats/eventdesc.htm
146
http://www.pso.ahrq.gov/formats/commonfmt.htm
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of Serious Reportable Events (SREs) to assist states with implementing and improving patient
safety reporting systems. This list of SREs was updated in 2006, identifying 28 adverse events
that are serious, largely preventable, and of concern to healthcare providers, consumers, and
other stakeholders.147 There are six categories of SREs, including:
•
Surgical events;
•
Product or device events;
•
Patient protection events;
•
Care management events;
•
Environmental events; and
•
Criminal events.
“Patient death or serious disability associated with an electric shock while being cared for in a
healthcare facility” is specifically included as one of the environmental SREs.
In order to assist hospitals with the development of their reporting systems, JCAHO published a
document in 2007, Sentinel Event Policy and Procedures,148 which defines occurrences that are
subject to review and considered sentinel events:
•
Any unanticipated death or major permanent loss of function, not related to the natural
course of the patient’s illness or underlying condition;
•
Suicide of any patient receiving care, treatment and services in a staffed around-the-clock
care setting or within 72 hours of discharge;
•
Unanticipated death of a full-term infant;
•
Abduction of any patient receiving care, treatment and services;
•
Discharge of an infant to the wrong family;
•
Rape;
147
National Quality Forum, “Serious Reportable Events in Healthcare 2006 Update: A Consensus Report,” National
Quality Forum, Quality Connections, Washington DC, 2007.
148
http://www.jointcommission.org/SentinelEvents/PolicyandProcedures/
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•
Hemolytic transfusion reaction involving administration of blood or blood products
having major blood group incompatibilities;
•
Surgery on the wrong patient or wrong body part;
•
Unintended retention of a foreign object in a patient after surgery or other procedure;
•
Severe neonatal hyperbilirubinemia (bilirubin >30 milligrams/deciliter); and
•
Prolonged fluoroscopy with cumulative dose >1500 rads to a single field or any delivery
of radiotherapy to the wrong body region or >25% above the planned radiotherapy dose.
The Center for Medicare and Medicaid Services (CMS) developed of list of hospital-acquired
conditions, which is divided into ten categories.149 CMS uses the list to determine
reimbursement rates, which are affected by hospitalizations complicated by these categories of
conditions not present on admission. “Electric shock” is a condition included in the subset of
events for the category “falls”. The ten categories of hospital-acquired conditions are as follows:
149
•
Foreign object retained after surgery;
•
Air embolism;
•
Blood incompatibility;
•
Pressure ulcers (stages III and IV);
•
Falls;
•
Manifestations of poor glycemic control;
•
Catheter-associated urinary tract infection;
•
Vascular catheter-associated infection;
•
Deep vein thrombosis/pulmonary embolism; and
•
Surgical site infection.
Fiscal Year 2009 Final Inpatient Prospective Payment System Rule, 73 Fed. Reg. 48434, 48471 (August 19,
2008)
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The NQF, JCAHO, CMS and AHRQ serious event lists are nationally recognized lists used in
the development of adverse event reporting systems.150 It should be noted that these lists differ
in the types of adverse events to be reported.
2.4.1.2
Federal Databases
2.4.1.2.1 FDA MAUDE Database
FDA receives reports of adverse events involving medical devices through the Manufacturer and
User Facility Device Experience (MAUDE) database. The data consists of voluntary reports
since June 1993, user facility reports since 1991, distributor reports since 1993, and manufacturer
reports since August 1996. The data is web searchable; however, there are limited keyword and
search capabilities.151 The data is also publically available for download to create a searchable
database. However, “MAUDE data is not intended to be used either to evaluate rates of adverse
events or to compare adverse event occurrence rates across devices.”
A 2004 review of the MAUDE database found that “user error” and “improper use” are the two
most often cited reasons for patient injury. The review concluded that since most of the entries
in these databases are manufacturer-generated, it is not surprising that their reports appear to
shift responsibility and risk to the clinician and health care organization.152
The MAUDE database files of incident reports ranging from the start of data collection in 1996
through August 2010 were downloaded and searched in Microsoft Excel. Each incident report
contains an entry which specifies the location where the incident occurred. Many incident
reports left this entry blank, so it is difficult, if not impossible, to determine the incident location.
Therefore, only incident reports which contained valid location entries were included in the
search. There were 518,384 incident entries with a specified location. Of these, only 92
incidents occurred in an operating room, and none of these 92 incidents involved electric shocks.
150
Rosenthal Jill, Takach Mary, “2007 Guide to State Adverse Event Reporting Systems,” State Health Policy
Survey Report, V1:1, Publication # 2007-301, National Academy for State Health Policy, Portland, ME, 2007.
151
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.CFM
152
Epstein Alice L, Harding Gary H, “Risk Management” Chapter 56 in Dyro Joseph F, ed. Clinical Engineering
Handbook, Elsevier Inc, Burlington MA, 2004.
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2.4.1.2.2 US Department of Defense
In response to the IOM 1999 report, the DOD established the Military Health System Patient
Safety Registry (MHSPSR) in 2001.153 The registry accepts monthly reports via an electronic
system from all military treatment facilities. The database incorporates event codes based on
JCAHO reportable event categories. The reports of adverse events, close calls, and root cause
analyses are reviewed and analyzed by the Patient Safety Center. They, in turn, execute action
plans to address patterns of patient care errors, produce quarterly patient safety newsletters, hot
topic articles, quarterly reports, and patient safety training sessions. However, all information is
protected from general release.154
2.4.1.3
State Databases
Medical event reporting systems have been adopted by 26 states plus the District of Columbia.155
Of these, 25 states and the District of Columbia have adopted mandatory reporting systems, and
one state (Oregon) has adopted a voluntary reporting system. Twelve states and the District of
Columbia use the list of SREs compiled by NQF, and the other 14 states use their own lists of
events to be reported. States using the NQF SREs are: California, Connecticut, District of
Columbia, Illinois, Indiana, Minnesota, Nevada, Oregon, Maryland, New Jersey, Vermont,
Washington, and Wyoming. States using state defined lists are: Colorado, Florida, Georgia,
Kansas, Maine, Massachusetts, New York, Ohio, Pennsylvania, Rhode Island, South Carolina,
South Dakota, Tennessee, and Utah. Table 9 lists the states with adverse medical event reporting
systems.
153
DOD Instruction 6025.17, 2001.
154
Davis Mary Ann, Rake Geoffrey W, “Implementation of a Data-based Medical Event Reporting System in the
U.S. Department of Defense,” Advances in Patient Safety: from Research to Implementation, Volume 3:
Implementation Issues, National Library of Medicine, 2005. Accessed June 2010:
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=aps3&part=A4734
155
Rosenthal Jill, Takach Mary, “2007 Guide to State Adverse Event Reporting Systems,” State Health Policy
Survey Report, V1:1, Publication # 2007-301, National Academy for State Health Policy, Portland, ME, 2007.
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Table 9. List of States using Adverse Medical Event Reporting Systems
State
Start date
155
Publicly available
annual reports or event
summaries
Electric shock
category included in
reports or event
summaries
Reported shock
incidents
CA
7/2007
Yes
Yes
1 (2008/2009)
CO
1988, revised 4/1997, 2005
Yes
No
N/A
CT
10/2002, revised 5/2004
Yes
Yes
0 (2004-2009)
DC
7/2007
No
N/A
N/A
FL
1985, revised 1998, 2003, and
2008
Yes
No
N/A
GA
2003
No
N/A
N/A
IL
1/2008
No
N/A
N/A
IN
2006
Yes
Yes
0 (2006-2009)
KS
1988
No
N/A
N/A
MA
1980’s, revised 1995
No
N/A
N/A
MD
3/2004
Yes
No
N/A
ME
2004
Yes
No
N/A
MN
enacted 4/2003, revised 2007
Yes
Yes
0 (2003-2009)
NJ
1990, updated system
operational 2/2005
Yes
No
N/A
NV
enacted 2003, revised 1/2005
Yes
Yes
0
NY
10/1985, electronic reporting
added in 1998
Yes
No
N/A
OH
1995, new law enacted
4/2007
No
N/A
N/A
OR
5/2006
Yes
No
N/A
PA
1998, revised for 4/2004
Yes
No
N/A
RI
1994
Yes
No
N/A
SC
1976, amended 2006
No
N/A
N/A
SD
Regulated in 1987, updated in
1995 and 2000, statute
created 1/2006
No
N/A
N/A
TN
Prior to 1999, revised 2002
Yes
No
N/A
UT
10/2001, revised 4/2007
Yes
No
N/A
VT
Statute 7/2006, rule adopted
for 1/2008
Yes
No
N/A
WA
Regulation 1995, statute 2006
Yes
Yes
0 (2004-2009)
WY
7/2005
Yes
Yes
0 (2005-2008)
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Table 9 shows that this literature search discovered only a single electrical incident included in
the state annual reports. Some state annual reports do not explicitly list electric shock data, but
may include it in categories such as “other” or “miscellaneous.” The NQF list specifies an event
that is classified as “environmental” and specifically called “patient death or serious disability
associated with an electric shock while being cared for in a healthcare facility.” States that use
the NQF list collect data on electric shock incidents under this event classification, but do not
necessarily include this data in annual reports or event summaries. For example, the District of
Columbia, Illinois, Maryland, New Jersey, Oregon, and Vermont use the NQF list, but do not
include electric shock data in their annual reports or event summaries.
The state reporting systems differ on the criteria used to define adverse events, the amount and
type of information submitted about patients, and whether hospitals’ submissions include
information about the causes of events. This affects how information about adverse events is
reported and the types of events that are reported, which in turn makes it difficult to interpret the
findings.
2.4.1.4
Foreign Databases
In the United Kingdom, the Medicines and HealthCare Products Regulatory Agency (MHRA)156,
formed in 2003, regulates the use of all healthcare devices and medicines within the United
Kingdom. Problems with medical devices are reported to MHRA from other authorities in the
United Kingdom, voluntary reporting by users, voluntary reporting by manufacturers, and
obligatory post marketing surveillance by the manufacturers.157 Healthcare workers are
encouraged to self-report any device failure. MHRA analyzes and disseminates the incident data
and provides Medical Device Alerts and publically available annual reports. In the annual
reports, however, specific category events, such as electric shock are not reported; only device
group statistics are available, for example “surgical equipment.”158
156
www.mhra.gov.uk
157
Fenlon Stephen, “The anaesthetist and the Medicines and Healthcare Products Regulatory Agency,” in Davey
Andrew J, Diba Ali. eds. Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
158
http://www.mhra.gov.uk/Publications/Safetyguidance/DeviceBulletins/CON082072, accessed September 2010.
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The United Kingdom also has formed the National Patient Safety Agency (NPSA), which
receives medical device-related adverse incidents anonymously. This data is analyzed to detect
trends and identify areas to improve medical practices.157
The Australian Government Department of Health and Ageing Therapeutic Goods
Administration (TGA) has also developed a medical device incident database.159 Since 2001,
TGA has published general statistics on the adverse events submitted to its medical device
Incident Report Investigation Scheme (IRIS). The IRIS system is used to record and track
reports of adverse events or problems associated with medical devices submitted to TGA. TGA
also releases safety alert articles to provide important information about medical device
incidents.160
The Australian Patient Safety Foundation (APSF) a non-profit independent organization
dedicated to the advancement of patient safety has developed the Advanced Incident
Management System (AIMS)161, a software to collect, classify, and manage incident reports from
near misses to sentinel events.
The APSF has contributed to the World Health Organization (WHO) patient safety project to
develop an international classification for patient safety.162 In the WHO final report, a
framework for classifying incident types for reporting is diagramed, and “exposure to electricity”
is a subset of incident type “Patient Accidents.” It is unknown at this time if this newly
developed international classification is used by any adverse reporting databases.
2.4.1.5
Independent Database
The National Aeronautics and Space Administration (NASA) developed the Patient Safety
Reporting System (PSRS)163 jointly with the VHA.164 The PSRS is designed to be
159
http://www.tga.gov.au/problem/iris/statistics.
160
http://www.tga.gov.au/problem/iris/iris-index.htm
161
http://www.apsf.net.au/products.php
162
The Conceptual Framework for the International Classification for Patient Safety (v.1.1) - Final Technical Report
and Technical Annexes, World Health Organization, 2009. accessed September 2010:
http://www.who.int/patientsafety/implementation/taxonomy/icps_download/en/index.html
163
http://www.psrs.arc.nasa.gov, accessed September 2010.
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complementary to a medical facility's internal system, or a primary system responsible for
capturing close calls, events, patient safety concerns, and suggestions. This is a confidential and
non-punitive program, as NASA is an independent research organization without regulatory or
enforcement interest. Prior to development of the PSRS, NASA administered a similar program,
the Aviation Safety Reporting System (ASRS) for more than 30 years with over 850,000 reports.
An agreement is necessary between a healthcare organization and NASA to have access to
publications, such as a quarterly or monthly newsletter.
2.4.1.6
Case Histories – Sentinel Alerts
ECRI is a nonprofit health research agency that periodically reviews problems that have occurred
with medical devices and lessons learned. ECRI has a web-based Problem Reporting Network165
for healthcare providers, patients, and manufacturers to voluntarily report medical device related
incidents and deficiencies. ECRI analyzes the data it receives for specific hazards and publishes
Medical Device Safety Reports (MDSR)166 which are medical device incident and hazard
information independently investigated by ECRI. ECRI focuses on prevention or reduction of
medical device risks to patient care and healthcare worker safety. In ECRI’s Health Alerts
Database, there are eleven MDSRs related to electric shock and or electrocution, excluding those
MSDRs associated with emergency defibrillation:
Electrical Safety Requirements: Patient Care Areas versus Non-Patient-Care Areas, 1998
Lesions and Shocks during Iontophoresis, 1997
Extension Cords and Multiple Outlet Strips, 1996
Leakage Current Limits for Electronic Equipment Used in Non-Patient-Care Areas, 1996
Electronic Equipment Mounted on IV Poles, (spills on electrical equipment), 1993
Risk of Electric Shock from Patient Monitoring Cables and Electrode Lead Wires, 1993
Q&A Regarding Leakage Current Measurements, Powering Lasers, Electrical Outlets
and Extension Cords, 1993
164
http://www.patientsafety.gov/faq.html#OnlyPSRS, accessed September 2010.
165
https://www.ecri.org/Pages/ReportAdeviceProblem.aspx
166
http://www.mdsr.ecri.org/default.aspx
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OR Renovations and the Use of Isolated Power and Explosion-Proof Plugs, 1992
Connection of Electrode Lead Wires to Line Power, 1987
Sterilization of Medical Devices (caused electrical plug degradation) 1979
Electrical Plugs: A Compendium of Problems, 1979
JCAHO maintains a Sentinel Event Database, where they collect data from the review of sentinel
events, root cause analyses, action plans, and follow-up activities related to self-reported
incidents. They analyze the data for significant frequency and trends to identify specific sentinel
events that form the basis of Sentinel Event Alerts published when appropriate, describing
common underlying causes and suggested steps to prevent occurrences in the future. JCAHO
has identified 45 issues from February 1998 through June 2010.167 However, only one issue is
related to electricity: #37 Preventing adverse events caused by emergency electrical power
system failures, September 2006.
In summary, development of the medical industry adverse event reporting database structure has
been relatively recent, occurring over the past 10 years. A consistent standard of event reporting
and presentation of the resulting data is not available, making it challenging to specify an electric
shock incidence rate in hospital operating rooms.
2.4.2 Workplace Injury and Fatality Databases
Bureau of Labor Statistics (BLS) produces two widely used sources of data on occupational
fatalities and injuries in the United States. The annual Survey of Occupational Injuries and
Illnesses (SOII) produces national injury estimates and rates from a sample survey of business
establishments. The SOII data provides case counts by industry, occupation, source of injury,
nature of injury, part of body affected, and type of event. This database contains neither case
narratives for individual injury incidents nor information about risk factors. The Census of Fatal
Occupational Injuries (CFOI) identifies high-risk demographic and industry/occupation groups
and includes a case narrative. However, since both of these databases were designed to
accommodate all types of occupational fatalities, they do not contain sufficient detail to
167
http://www.jointcommission.org/SentinelEvents/SentinelEventAlert/
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specifically identify electric shock incidents in a hospital operating room, and can only identify
contact with electric current in the general healthcare industry and occupation.
The SOII data on non-fatal cases involving days away from work was reviewed for contact with
electric current each year from 2003 to 2008. The occupational industry sector, Health Care and
Social Assistance, records show that 210, 140, 260, 200, 120, and 90 cases occurred per year
from 2003 to 2008, respectively. It is probable that most, if not all of these cases involved nonoperating room work, however, this is impossible to determine, as case narratives are not
recorded. A similar check of CFOI data revealed no reportable deaths from contact with electric
current in healthcare industries or occupations.
Other general workplace injury databases, including general electrical incidents are identified;
however, these databases were not reviewed:
•
IEEE Electrical Safety Resource Center Website,
standards.ieee.org/esrc/case_histories.html
•
Occupational Hazards Website, http://www.occupationalhazards.com
•
http://www.safteng.net/Incident_Alert_Archives/Electrical%20Accidents.htm
•
US DOE Operating Experience Summary contains investigation reports,
http://tis.eh.doe.gov/paa/ oesummary.html
•
DOE Hanford, http://www.hanford.gov/lessons/sitell/funccats/electric.htm
•
Naval Facilities Engineering Command,
http://www.navfac.navy.mil/safety/site/topics/electrical.htm
•
National Electronic Injury Surveillance System (NEISS)
•
National Health Interview Survey (NHIS)
•
State-based Trauma Registries
2.4.3 Trends in Adverse Event Reporting
In the literature, a number of trends in adverse event reporting were identified that would have
effects on the electric shock incidence rate in hospital operating rooms. The following subsections summarize these trends and their possible effects.
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2.4.3.1
Trends in Medical Device Adverse Events
In 2008, the US Government Accountability Office (GAO) reported that the number of adverse
event reports associated with medical devices increased substantially from 2000 to 2006.168
Upon further review of possible causes of the increase in adverse event reports several
shortcomings were identified. In 2008, the FDA reported that they were unable to review all of
the adverse event reports received which affected their ability to understand the risks related to
the use of medical devices. In addition, the FDA efforts to review class III devices to a more
stringent standard were not complete. In 2009 GAO determined that the FDA has not met a
statutory requirement to inspect certain domestic medical device manufacturers every two
years.168 The shortcomings of the FDA in premarket and postmarket activities would tend to
increase the electric shock incidence rate in hospital operating rooms.
2.4.3.2
Underreporting of General Workplace Incidents
Underreporting of electrical injuries in the general workplace occurs due to a number of
reasons:169
•
Classifying workplace incidents varies depending on the available event information;
•
Employers vary in their effort or ability to report incidents;
•
Workplace cultures exert peer pressure that favors not recording electrical incidents;
•
Management is not rewarded for reporting and a track record of difficulties can affect
promotion and pay opportunities; and
•
Employees vary in their effort to report incidents, because drawing attention to an unsafe
act is not appreciated or in an employee’s best interest, as they are expected to conduct
themselves safely.
There have been a number of reporting studies regarding general workplace injuries. In 1986,
OSHA confirmed that employers underreport occupational injuries and illnesses.170 A 1987 BLS
168
GAO Testimony: Medical Devices Shortcomings in FDA’s Premarket Review, Postmarket Surveillance, and
Inspections of Device Manufacturing Establishments. GAO-09-370T. June 18, 2009.
169
Floyd HL, Andrews JJ, Capelli-Schellpfeffer M, Neil TE, Liggett DP, Saunders LF, “Safeguarding the Electric
Workplace: an overview of the state-of-the-art in electrical safety technology, work practices, and management
systems,” IEEE Industry Applications Magazine, pg.18-24, May/June 2004.
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study of 192 employers in Michigan and Missouri found that injuries were underreported by 10%
and injuries involving lost workdays were underreported by 25%.170 In 1990, a report by GAO
identified three major reasons for underreporting:
1) intentional under recording in response to OSHA inspection policies or employer
safety competitions
2) lack of understanding of the recording and reporting system
3) lack of priority placed on recordkeeping by employers, lack of supervision of
recordkeeping.170
In studies published between 2004 and 2006, researchers demonstrated that the BLS SOII
database captures only 33 to 67% of all occupational injuries and illnesses.170 It is recommended
that the SOII database not rely solely on employer based data sources. The SOII surveillance
system should include basic changes to address the reasons that lead to underreporting.171 the
following conceptual filters lead to underreporting:171
•
The worker needs to report the injury/illness or medical care to supervisor;
•
Healthcare providers need to recognize work-relatedness;
•
Treatment needs to be charged to workers’ compensation;
•
Healthcare providers need to participate in an occupational disease reporting system; and
•
The injury/illness needs to be recorded by the employer.
Underreporting of workplace injuries artificially decreases the electric shock incidence rate in
hospital operating rooms.
170
Friedman Lee S, Forst Linda, “The impact of OSHA recordkeeping regulation changes on occupational injury
and illness trends in the US: a time-series analysis,” Occupational Environmental Medicine, V64:454-460. 2007.
171
Rosenman KD, Kalush A, Reilly MJ, Gardiner JC, Reeves M, Luo Z, “How much work-related Injury and Illness
is Missed by the Current National Surveillance System,” Journal Occupational Environmental Medicine,
V48:4:357-365. 2006.
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2.4.3.3
Underreporting of Medical Incidents
There are several examples of underreporting workplace injuries in the medical industry.
Underreporting of percutaneous injuries is common, with rates of up to 96% published.172 In
2010, a survey of 30 surgeons was performed to document their experiences using two medical
devices, a cat’s paw retractor and Gillies’ forceps.173 Twenty-eight respondents had an incident
with the cat’s paw retractor, with only one reporting an injury to the hospital occupational health
department, for a total of 96.4% underreporting. Twenty-two respondents had an incident with
the Gilles’ forceps, with none reporting an injury to the hospital occupational health department,
for a total of 100% underreporting.173
More serious is the trend in underreporting of adverse events involving patients in the medical
industry. The tendency is to under-report adverse events, especially when a practitioner
perceives an element of personal responsibility.174
Additional reasons for underreporting adverse events are documented.175 Those responsible for
investigating and reporting are not privileged to all patient safety incidents, because of the
litigious nature of the health care industry. Physicians, nurses, healthcare workers and hospitals
treat all medical adverse events as confidential. As a result of this increased pressure to reduce
risk, disciplinary action is often the first recourse for a mistake. This leads to further medical
mistakes, as root causes are not identified through failure investigations after an adverse event
has occurred. Eliminating an individual from a position seems to be normal to solve problems.
NQF, who assists the healthcare industry with the development of adverse event reporting
databases, comments in their 2010 report, “the fear of retaliation against facilities or individuals
172
Holodnick CL, Barkauskas V, “Reducing percutaneous injuries in the OR by educational methods,” AORN. J.
V72:461-476. Sept. 2000.
173
Fitzgerald Eilis, Sharkey Aidan, “Safety in the operating room: Are we neglecting ourselves?” Journal of Plastic,
Reconstructive and Aesthetic Surgery, V63:474-475. 2010.
174
Fenlon Stephen, “The Anaesthetist and the Medicines and Healthcare Products Regulatory Agency,” in Davey
Andrew J, Diba Ali, eds. Ward’s Anaesthetic Equipment, 5th edition. Elsevier Saunders, 2005.
175
Patail Bryanne, “Patient Safety and the Clinical Engineer,” Chapter 55 in Dyro Joseph F, ed. Clinical
Engineering Handbook, Elsevier Inc, Burlington MA, 2004.
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fuels efforts to resist reporting and can shift the focus away from care, hamper morale, and foster
distrust, all of which undermine efforts to establish a culture of safety.”176
Underreporting of adverse medical events artificially decreases the electric shock incidence rate
in hospital operating rooms.
2.4.4 Literature Citations of Electrical Incidents
The medical literature was searched for electric shock incidents occurring in hospital operating
rooms. The following sections summarize electric shock events and case studies that were found
during the literature review. Some of the citations were only found through examination of the
reference lists of other relevant documents. Therefore, it should not be expected that the
following list of incidents is complete.
2.4.4.1
1960s
At least eleven incidents of shock and ventricular fibrillation during surgical procedures in the
literature were identified from 1960-1967.177 Five of these incidents were attributed to line
current leakage of devices and implanted cardiac pacemakers, three of the incidents were
attributed to ungrounded and/or defective medical equipment (i.e. cardiac monitor, soldering
iron, and injection pump) and three were of undetermined or uncited cause.
Two incidents occurred from 1962-1963 not already referenced above, involving ventricular
fibrillation by currents less than physical perception leading directly to the heart via pacemaker
electrodes and catheters.178
2.4.4.2
1970s
In the early 1970s an incident occurred involving a urologist that was burned on the eyebrow,
using a scope while standing on a grounded floor and performing ground-referenced
176
National Quality Forum, “The Power of Safety: State Reporting Provides Lessons in Reducing Harm, Improving
Care,” National Quality Forum, Quality Connections, Washington DC, 2010.
177
Bruner John, “Hazards of Electrical Apparatus” Anesthesiology, V28:2:396-425. Mar/Apr 1967.
178
Hull CJ, “Electrocution Hazards in the Operating Theatre,” Br. J. Anaesth. V50:647. 1978.
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electrosurgery in a saline-soaked environment. The urologist was wearing conductive booties
over bare feet at the time of the incident.179
An incident occurred where a patient connected to an electrosurgical return plate was intensely
shocked when an electrocardiogram (EKG) device was powered by an incorrectly wired outlet
with the ground and neutral leads transposed.180 The physician also experienced a minor shock.
The building code for the city had no requirement for standardized wiring polarity, and it was
found that 20% of the outlets in the hospitals operating rooms had reversed polarity.
2.4.4.3
1980s
In retrospect to failed attempts to modify the 1973 edition of NFPA 56A with respect to
permitting the use of grounded electrical power instead of isolated power, an attempt was made
to quantify the risk of electric shock in hospitals. Arguments indicate that electrical safety
precautions usually control a larger share of the hospital’s biomedical equipment safety budget
than is justified by the actual hazard levels.181
2.4.4.4
1990s
An incident involving a bipolar electrosurgical device with an internal IT with damaged ceramic
insulator mounts occurred, because it had been dropped. The damage caused the IT to become
connected to ground.182 The medical device was powered by an isolated power supply in
conjunction with a LIM. A resident was severely shocked while gripping a patient’s hand while
simultaneously in contact with the operating room table frame when the electrosurgical device
was activated.
179
Hyndman Bruce H., “A Thirty-Two Year Perspective on a Clinical Engineer’s Contributions to Patient Safety,”
IEEE 2004.
180
Atkin David H, Orkin Louis R, "Electrocution in the operating room," Anesthesiology, V38:2:181-183. 1973.
181
Ridgeway M, “Guidelines for clinical engineering programs – Part III: the risk of electrical shock in hospitals,” J.
Clinical Engineering. V6:1:53-63. 1981
182
Gilbert Timothy B, Shaffer Michael, Matthews Marianne, “Electric Shock by Dislodged Spark Gap in Bipolar
Electrosurgical Device,” Anesthesia & Analgesia, V73:355-357. 1991.
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A 1993 study of the first 2,000 incidents reported to the Australian Incident Monitoring
System.183 There were six cases in which an electrical hazard was identified. There were two
incidents involving electric shock, where anesthetists received shocks after touching a faulty
device and the chassis of another device simultaneously. Class I equipment has ground
conductors capable of conveying leakage currents from faulty devices via the operator,
especially if they have wet skin, which is very common with anesthetists.184 Another reported
incident involved an accidental spill of a fluid container onto a blood pressure monitor, which
caused a malfunction of the blood monitor. This incident caused harm to the patient, as another
replacement monitor was not available.183
Four electrical shock incidents that took place in the in the operating rooms at the Naval Hospital
Oakland in Oakland, California, which had grounded power supply systems installed, were
reported:185
•
Case 1 involved an intermittent problem in a neurosurgical video recorder and television.
When a technician unlocked the cabinet containing the power supply, he was shocked by
an arc jumping from the cabinet to his key. There may have been a possible ground
problem, but no specific fault was identified.
•
Case 2 involved a housekeeping staff member who was shocked while using a hydro-vac
with a frayed power cord to clean a wet floor.
•
Case 3 involved an operating room technician who received a shock while plugging an
electrosurgery device into a wall outlet with loose wire.
•
Case 4 involved an operating room technician who was shocked adjusting the dimmer
switch of surgical field lights, which had recently been replaced, however, no
abnormality was found.
183
Singleton RJ, Ludbrook GL, Webb RK, Fox MA, “The Australian Incident Monitoring Study. Physical injuries
and environmental safety in anaesthesia: an analysis of 2000 incident reports,” Anesthesia and Intensive Care,
V21:5:659-663. 1993.
184
Taktak AFG, Brown MC, “Evidence-Based Analysis of Field Testing of Medical Electrical Equipment,”
Proceedings of the 28th IEEE EMBS Annual International Conference, New York, pg4078-4080, August 30September 3, 2006.
185
Day Franklin J, “Electrical Safety Revisited: A New Wrinkle,” Anesthesiology V80:220-221. 1994.
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Two incidents of cardiac microshock were reported, where capacitive coupling occurred between
a unipolar electrosurgical pen tip and the reference EKG electrode disconnected from the patient,
but connected to the pulmonary artery catheter.186
Two incidents of microshock were reported in 1992, where capacitive coupling occurred
between a unipolar electrosurgical pen tip and numerous metallic trocars in close contact in the
abdomen.187 Trocars for laparoscopic surgery are now made of plastic.
An incident involving a stopper becoming detached from an urimeter collection bag occurred,
causing fluid to cascade over an extension cord power tap on the operating room floor. This
caused the power to fail in the entire operating room.188
2.4.4.5
2000s
Two incidents were reported where power to the operating room was lost during open heart
surgery, with the cause determined to be humidity in the outlet powering the fluid and blood
heater.189 It is recommended that sealed plugs be used and anesthesia equipment not be used as
an electrical supply for other apparatus.
An incident occurred in Australia where an ungrounded operating table and placement of a
(damaged) power cord under the operating room table support leg led to leakage current
provided by another device (firstly an image intensifier and secondly an electrosurgical device)
through the “live” table to earth, causing arc flashing and tripping of the GFCI into which the
severed cord was plugged.190
186
McNulty SE, Cooper M, Staudt S. “Transmitted radiofrequency current through a flow directed pulmonary artery
catheter,” Anesthesia & Analgesia, V78:3:587-589. 1994.
187
Litt Lawrence, Ehrenwerth Jan, “Electrical Safety in the Operating Room: Important Old Wine, Disguised New
Bottles,” Anesthesia & Analgesia, V78: 417-419. 1994.
188
Nixon MC, Ghurye M. “Electrical failure in theater—a consequence of complacency?” Anaesthesia, V52: 88-89.
1997.
189
Andersen C, Pold R, Nielsen HD, “Dampness in an electric plug as a cause of electricity failure in an operation
theatre,” Ugeskr.Laeger, V162:6:799-800. Feb. 2000.
190
Courtney NM, McCoy EP, Scolaro RJ, Watt PA, “A Serious and Repeatable Electrical Hazard – Compressed
Electrical Cord and an Operating Table,” Anaesthesia & Intensive Care, V34:3:392-396. 2006.
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An electric shock incident occurred during a cystoscopy procedure, where an operating room
nurse was shocked while plugging in an argon beam coagulation unit into an extension cord with
a four-receptacle metal junction box with rubber and plastic casing in a wet environment (i.e.
floor cleaned by “throwing buckets of water on the floor” before the operation and additionally
there was normal cystoscopy irrigation fluids on the floor).191
In 2008, a search was conducted on more than 800,000 reports submitted since 2004 to the
Pennsylvania Patient Safety Advisory.192 The keywords “shock” and/or the phrase “line
isolation monitor” in reports with operating room as the location resulted in the five reports
summarized here:
•
A staff member reported receiving a shock while touching the patient and anesthesia
machine during the same time that the surgeon touched the patient with a Bovie pencil.
•
While performing cystoscopy and a transurethral resection of the prostate using an Erbe
Bovie CE 7090 on a patient under spinal anesthesia, the patient jumped and felt
something go up the back. The surgeon also felt a shock in the finger twice. At the same
time, the Bovie stopped working. The Bovie cord and electrode were both changed, and
the Bovie started to work.
•
While using a Trivex light source machine, the light appeared to not be as bright as
normal. A staff member was shocked while trying to reposition the light cord in the
machine. The machine sparked a few times at the light source and began to smell hot.
The machine was turned off, unplugged, and taken out of service.
•
An employee conveying a metal cart pushed the auto-open button on the outside of the
operating room doors and received a large shock that could be felt from arm to feet.
Another employee holding onto the other end of the metal cart also received a shock.
•
A KCI Air Bed (SN.BKOK 01612) was wired incorrectly and set off the LIM alarm. The
air bed was rewired, correcting the problem.
191
Wills John H, Ehrenwerth Jan, Rogers Dan, “Electrical Injury to a Nurse Due to Conductive Fluid in an
Operating Room Designated as a Dry Location,” Anesthesia & Analgesia, V110:6:1647-1649, 2010.
192
PA Patient Safety Advisory, 2008 Dec: 5(4):110.
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3 Gap Analysis
In the previous section, a literature survey was summarized to provide a comprehensive view of
the hospital operating room electrical environment in order to facilitate hazard analysis by an
individual hospital, to evaluate whether a particular operating room should have a “wet
procedure location” or “dry location” electrical classification. An analysis of the available
literature with a particular focus on utilization of the data to support a hazard assessment
methodology revealed gaps in the data that are necessary to support a detailed quantitative
hazard assessment methodology for evaluating operating rooms as a wet or dry location. The
following sections identify relevant gaps in the data and provide suggested means for obtaining
the data in the future.
3.1 Operating Rooms as Wet Procedure Locations or Dry
Locations
In the medical literature, surgeons, anesthesiologists and nursing staff identify that common
knowledge about blood and fluid loss and irrigation practices for specific surgeries is gained by
experienced practitioners. However, while evaluation of blood and fluid loss during surgery is
identified as a critical step to monitoring a patient’s health, medical literature has cited the
difficulty of operating room staff to quantify these losses accurately during operating room
procedures.193,194
There is a plethora of clinical study information on many types of surgical operations available
in the literature, too many to review for the scope of this study. However, the data can be
hospital and even surgeon specific, which contributes to higher data uncertainty.
While health care professionals have provided opinions of the nature of the operating rooms and
examples of types of events that lead to wet environments, clinical studies of the frequency at
193
Eipe Naveen , Ponniah Manickam, “Perioperative Blood Loss Assessment – How Accurate?” Indian J. Anaesth.
V50:1:35-38. 2006.
194
Boyd Harry R, Stanley Connie, “Sources of Error when Tracking Irrigation Fluids During Hysteroscopic
Procedures,” J. Amer. Assoc. of Gynecologic Laparoscopists. V7:4:472-476. 2000.
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which these events (such as spills) occur have either not been performed or are not available in
the general medical literature.
Kaiser Permanente performed a survey of staff working in their group of hospitals, but the scope
of the study was not clear from the condensed presentation of the results.195 A well vetted
clinical study and/or questionnaire-based survey with a carefully focused scope to identify the
frequency and quantity of liquid releases for a statically based selection of hospitals would be
valuable.
3.2 Adverse Event and Incident Reporting
3.2.1 Database Information
Analysis of the available databases and presentation of the resulting statistics often revealed that
there was not enough specific information to determine cause, or at least verify that the event
occurred in an operating room during a surgical procedure.
For an electrical incident case history to be meaningful, it should include the following
information:196
•
Summary of the incident describing the scenario including who, what and where;
•
Resulting or potential injury, including the extent of the injury;
•
Background information describing clarifying elements, such as the environment,
procedure compliance, contributing factors, and other circumstances; and
•
Lessons learned, summarizing conclusions and corrective actions taken.
NQF reports that significant incongruities remain among the state adverse event reporting
systems, relating to differing implementation approaches and differing perspectives toward
195
196
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words,” 2004 AIA/ASHE International Conference
on Planning, Design & Construction, March 2004.
Eastwood Kim, Hancharyk Brent, Pace David, “Making the Case for Safety,” IEEE Industry Applications
Magazine, V11:3:23-29. May/June 2005.
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reporting patient safety events.197 This has led to inconsistent results for improving the adverse
outcome rate of events.
The fact that AHRQ is implementing and will maintain a national based NPSD198 that
incorporate common formats for standardized data collection is promising. However, it is
unclear from the description of the AHRQ common formats if electric shock adverse events will
be tracked. It is also undetermined as to how AHRQ plans to analyze the statistics and to what
extent they will disclose their findings. For example, some states require reporting of adverse
events classified using the NQF list of 28 SREs, however, the types of events and how they are
reported differ.
The use of quality control criteria to assess data quality of incident reports, placing emphasis on
missing data for key variables, timeliness of reporting, and unresolved duplication is
encouraged.199 Using the North American Association of Central Cancer Registries quality
control criteria200 to assess the data quality is recommended. The adverse event database
reporting systems should implement a means of assessing the quality of the adverse event reports
received from the hospitals and convey that information in their reports.
Until a more consistent standard of adverse event reporting and presentation of the resulting data
is available, evaluating or even estimating an electric shock incidence rate in hospital operating
rooms is challenging. State adverse event databases should provide incident statistics in all
categories and all sub-categories of adverse event classifications in the analysis reports. For the
purposes of evaluating an operating room as a wet or dry environment, the NQF list of 28 SREs,
which specifically includes electric shock as a reportable event, is the most useful event list. A
database using an adverse event list based on the CMS hospital acquired conditions should
197
National Quality Forum, “The Power of Safety: State Reporting Provides Lessons in Reducing Harm, Improving
Care,” National Quality Forum, Quality Connections, Washington DC, 2010.
198
Wright S, “Memorandum Report: Adverse Events in Hospitals: Public Disclosure of Information about Events”
OEI-06-09-00360, Department of Health & Human Services, Washington DC, January 5, 2010.
199
200
Friedman Lee S, Forst Linda, “Occupational Injury Surveillance of Traumatic Injuries in Illinois, Using the
Illinois Trauma Registry,” Journal Occupational Environmental Medicine, V49:4:401-410. 2007.
Havener LA, ed. North American Association of Central Cancer Registries. Standards for Cancer Registries
Volume III: Standards for Completeness, Quality, Analysis, and Management of Data. Springfield, Illinois:
October 2004.
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breakout the categories into the various tracked conditions. Details should be provided on the
types of events included in “other” categories.
In addition, having the ability to search an adverse event database for specific incident report
summaries (e.g. the MAUDE database) based on the adverse event classification lists which have
been vetted to remove personal data and other identifying is ideal. Identifying the root cause of
electric shock, the electrical equipment and safety systems involved, and the environmental
factors are important elements in a quantitative risk assessment.
3.3 Electrical System
3.3.1 Prevalence of Grounded vs. Isolated Electrical Systems across the
US
One aspect of evaluating an electric shock incidence rate is to consider the cause of the adverse
event, so as to provide a one to one comparison. When reviewing the adverse event database,
background information about the electrical system and other safety systems in place at the time
of the event is important to evaluating the event cause. The current ratio of isolated power in
comparison to grounded electrical systems utilized by hospitals in their operating rooms is
currently unknown. This ratio has an effect on interpretation of the incident data.
There is limited data on the number of grounded electrical systems in comparison to the number
of IPSs currently in use. A 2000 survey of the Kaiser Permanente group of hospitals indicated
that half of their operating rooms used IPSs and the other half used grounded systems.201 Due to
continuing hospital policy where all of their operating rooms are defined as dry locations, in
2008, out of 48 medical centers with 396 operating rooms, 22% had IPSs currently installed.202
Medical associations who monitor operating room usage or have access to hospital design
records do not track type of electrical systems installed in US hospitals:
201
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words,” 2004 AIA/ASHE International Conference
on Planning, Design & Construction, March 2004.
202
Kaiser Permanente, comment submitted to NFPA 99-2009 ROC, 2008.
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•
AHA does not track power systems installed in their annual survey of hospitals.203
•
ASHE does not track power systems installed.204
•
JCAHO does not track power systems installed.205
Another source of useful data regarding IPSs is how often the LIMs alarm or when IPSs trip. It
was discussed in the literature that a disadvantage of the IPS and LIM systems are “nuisance
alarms.” These records should be a part of hospital clinical and biomedical engineering
department maintenance and service request records. Starting in the 1980s, clinical engineering
departments analyzed data from service requests, including equipment, accessories and users.206
Quarterly reports of these statistics chosen as measures of performance were submitted to the
hospital’s safety and risk management committee. A field survey of hospital records to acquire
statistical data on maintenance is recommended.
3.3.2 Electrical System Costs
Another important aspect in the debate regarding evaluation of hospital operating rooms as wet
or dry locations is the cost difference of IPSs in comparison to grounded systems. In order to
perform a cost-benefit analysis, the following costs and benefits are applicable:207
•
Design fees;
•
Construction/installation;
•
Commissioning and staff training;
•
Routine maintenance;
•
Reduced damages due to cost to address health effects of injuries;
203
Review of the complete list of fields for the AHA Annual Survey Database,
http://www.ahadata.com/ahadata/PDFs/2008/SurveyFileLayout.xls
204
Personal communication with John Collins at ASHE.
205
Personal communication with Jerry Gevais an electrical engineer in the standards department at JCAHO.
206
Hyndman Bruce H., “A Thirty-Two Year Perspective on a Clinical Engineer’s Contributions to Patient Safety,”
IEEE 2004.
207
Meacham Brian J, Charters David, Johnson Peter, Salisbury Matthew, “Building Fire Risk Analysis,” Section 5
Chapter 12 in DiNennon et al, eds. SFPE Handbook of Fire Protection Engineering, 4th edition. NFPA, Quincy,
Massachusetts, 2008.
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•
Reduced medical liability suits; and
•
Reduced insurance premiums.
Upon review, the literature did not provide a balanced outlook on the construction and
maintenance costs given the significant variations in cost of living, materials, and labor wages
across the US. The following two sections summarize the electrical system cost information
obtained; further study is warranted.
3.3.2.1
•
Construction/Installation Costs
In 2007, an IPS panel may cost twice as much in comparison to a grounded panel with
GFCI breakers, and the estimated extra labor and material to install an IPS was
approximately 15% more.208
•
In 2000, the difference in cost for installing an IPS in comparison with a grounded system
was approximately $30,000 per operating room.209In 2008, the cost to install an IPS per
operating room was $71,500 for a retrofit and $42,900 for new construction.210 These
figures describe the total cost of the system, not the incremental cost of an IPS.
3.3.2.2
Maintenance Costs
It is reported in the literature that maintenance of an IPS includes regular testing to confirm that
the actual level of isolation meets appropriate standards and that LIMs are functioning
correctly.211 It is important for clinical personnel (such as operating room staff) and technical
personnel (such as clinical engineering staff) to understand the function of IPSs. In particular, it
is important to establish policies and procedures for staff response to LIM alarms.211
208
Schneider Electric and D Square D, “Isolated Power Systems (IPS) and Wet Locations in Healthcare Facilities Technical White Paper,” paper # 0104DB701, Schneider Electric, Palatine, IL, December 2007. static.schneiderelectric.us/docs/electrical%20Distribution/0104DB0701.pdf, accessed August 2010.
209
Vernon Walt, Nash Hugh, “Isolated Power: The Final (Two) Words,” 2004 AIA/ASHE International Conference
on Planning, Design & Construction, March 2004.
210
Kaiser Permanente, comment submitted to NFPA 99-2009 ROC, 2008.
211
Baretich Matthew F, “Electrical Power,” Chapter 109 in Dyro Joseph F, ed. Clinical Engineering Handbook,
Elsevier Inc, Burlington MA, 2004.
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Over the 30 year life of an IPS, it is estimated that there is an additional $197,000 in operating
costs (using 2008 dollars).212
212
Kaiser Permanente, comment submitted to NFPA 99-2009 ROC, 2008.
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4 Risk Assessment Methodology
The study presented in this report is intended for use by the NFPA Fire Protection Research
Foundation to assist with their decision making related to NFPA 99, Standard for Health Care
Facilities. Proper application of this report requires recognition and understanding of the
limitations of both the scope and methodology of the study.
The scope of the study was to gather information to assist the HEA-ELS in addressing the issue
of whether hospital operating rooms should be classified as wet procedure locations. This study
does not specifically address every possible electrical hazard. The end-user of this study is
expected to be knowledgeable of the operating room in question and exercise good engineering
judgment.
The risk assessment methodology forming the basis of the results presented in this report is
based on mathematical and statistical modeling of physical systems and processes, as well as
data from third parties. Given the nature of these evaluations, significant uncertainties are
associated with the various hazard and loss computations, some of which are accounted for in the
methodology, while other uncertainties (i.e., as-built construction details, modifications, current
conditions, material characteristics, etc.) cannot be readily incorporated into the analyses. These
uncertainties are inherent in the methodology and subsequently in the generated hazard and loss
results. These results are not facts or predictions of the risk that may occur as a result of future
events or any specific event; as such, the actual risk in a specific operating rom may be
materially different from those presented in this study. Furthermore, the assumptions adopted in
determining these loss estimates do not constitute the exclusive set of reasonable assumptions,
and use of a different set of assumptions or methodology could produce materially different
results.
The basis of a hazard analysis is to identify incident scenarios in order to evaluate risk by
defining the probability of failure, the probability of various consequences, and the potential
impact of those consequences. Risk is a function of the probability or frequency and
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consequence of a particular accident scenario. In a risk assessment, there are several steps in
order to evaluate, prioritize, and manage hazards and their associated risk:
1) Define the scope of the assessment;
2) System Description, compiling information needed for the risk analysis;
3) Hazard Identification, using aids such as experience, operations knowledge, what-if
analysis, fault tree analysis, failure modes and effects analysis, and event tree analysis;
4) Incident Enumeration, without regard to importance or initiating event;
5) Selection of Incidents, Outcomes, Cases, where one or more significant incidents are
chosen to represent all identified incidents;
6) Estimate Consequences, if consequences of an incident are acceptable at any frequency
the analysis of the incident is complete, if not acceptable then continue analysis;
7) Modify System to Reduce Consequences, if no feasible and economically viable
modifications available, continue analysis;
8) Estimate Frequencies, if frequency of an incident is acceptably low the analysis is
complete, otherwise continue analysis;
9) Modify System to Reduce Frequency, if no feasible and economically viable
modifications available, continue analysis;
10) Combine Frequency and Consequences to Estimate Risk, if risk estimate is below the
target or the strategy offers acceptable risk reduction, the analysis is complete;
11) Modify System to Reduce Risk, if no modifications are found than fundamental changes
to the system are necessary.
Risk analysis can range from simple screening studies to a detailed risk analysis involving large
numbers of incidents while using highly sophisticated frequency and consequence models. In
the cases where quantification of the frequency of an incident is less well understood and
historical data is not available, semi-quantitative risk analysis utilizing tools, such as risk
matrices, fault tree analysis, and event tree analysis methods to evaluate consequences are used.
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A risk assessment can be performed in order to assist the evaluation of particular hospital
operating room and associated expected procedures for electrical classification of the
environment as a wet or dry procedure location. One of the proposals currently being considered
by the NFPA 99 HEA-ELS committee during the 2011 ROP/ROC cycle, is the recommendation
to add a new code section as follows:213
4.3.2.2.8.3* Operating rooms shall be considered to be a wet procedure location unless
a risk assessment conducted by the health care governing body determines otherwise.
A.4.3.2.2.8.3 In conducting a risk assessment, the health care governing body should
consult with all relevant parties, including, but not limited to, clinicians, biomedical
engineering staff, and facility safety engineering staff.
In order to define the scope of the risk assessment, it is important to consider the current
definitions. The NEC provides the following definitions:
Dry Location: A location not normally subject to dampness or wetness. A location
classified as dry may be temporarily subject to dampness or wetness, as in the case of a
building under construction.
Wet Location: Installations underground or in concrete slabs or masonry in direct
contact with the earth; in locations subject to saturation with water or other liquids, such
as vehicle washing areas; and in unprotected locations exposed to weather.
Wet Procedure Location: Those spaces within patient care areas where a procedure is
performed and that are normally subject to wet conditions while patients are present.
These include standing fluids on the floor or drenching of the work area, either of which
condition is intimate to the patient or staff. Routine housekeeping procedures and
incidental spillage of liquids do not define a wet location.214
From these definitions, quantities of liquids that pool upon release are indicated as important.
Additionally, Appendix B of NFPA 99 provides explanatory material on the nature of electrical
hazards. The fundamental electrical hazard in a wet procedure location is an electric shock.
NFPA 99 Figure B.1.2.2.1(b)215 indicates the primary interrelated systems involved with the
213
NFPA 99 June 2011 Report on Proposals, 99-96, Log #CP330
214
National Electrical Code-2008, page 28.
215
NFPA 99-2005, page 99-172.
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fundamental hazard. There are three primary components in this hazard system: people,
equipment and the environment. The people involved are the patient and operating room staff,
such as surgeons, anesthesiologists, nursing staff, and other assistants. The equipment involved
includes the medical devices, electrical power supply, and electrical safeguards. The
environment includes conductive surfaces, such as the floor, plumbing, and any area made more
conductive by the additional presence of conductive liquids. The presence of liquids in the
environment can be intimately associated with the patient or with the room. The chance of a
person sustaining an electric shock is dependent on a combination of all three components.
The hazard system to best evaluate the hospital operating room as a wet or dry location can be
represented by the fault tree schematic in Figure 1. In the figure, in order to focus on the
possibility of a wet environment contributing to an electric shock hazard, the people are
necessary participants and the equipment is a contributing hazard. The equipment and associated
safeguards have multiple potential methods of malfunction that depend on the type of equipment
and the failure modes, such as aging and wear and tear. These failure modes are outside the
scope of the hazard assessment to evaluate the operating room environment. The environmental
component of the fault tree is the focus of the hazard assessment.
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Figure 1.. Fault tree for an electrical shock hazard in a hospital operating room
The following describes a risk assessment method to assist a healthcare governing body to
determine if their operating rooms (on an individual basis depending on expected usage) should
be considered a wet proceduree location.
4.1 Risk Ranking Based on Spill Size
The hazard scenario model of NFPA 99 Annex B (Figure B.1.2.2.1 (b)) identifies the key
elements necessary to lead to an electric shock hazard in the operating room. Figure 2
summarizes
es some example causal factors for electric shock in a fault tree format. The risk
ranking method proposed here assumes that the hazard of interest (electric shock) is fixed and
constant at a state designated as “severe.” The likelihood of electric shock is assumed to be a
function of liquid pool size only. This assumption focuses attention of the wet or dry nature of
the floor or work area surfaces. Other factors, such as the timing of the liquid release (i.e.
frequency of spills), the probability that an electrical medical device, including any safeguards,
safeguards is
in a fault condition, and the probability of contact with electrical equipment are either not
available or not well defined. Therefore, these probabilities are assumed to be automatically
present and equal to one,, so as to create an opportunity for an electric shock. Furthermore, it is
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assumed that a liquid release will occur. Thus, the only variable considered is the probability of
the human subject contacting the wet surface. Figure 3 summarizes this concept in the form of
an event tree. This is a conservative approach (i.e., this approach will tend to overestimate the
probability of exposure especially, because it is unlikely that a liquid release resulting in a liquid
pool will occur with every use of the operating room).
The probability of exposure is based on the volume of the liquid released. The probability of
personnel exposure to a subsequent liquid pool is calculated as the ratio of two areas: the pool
area divided by the unoccupied area of the operating room floor. The recommended algorithm is
given below:
•
Form a knowledgeable team of hospital staff (i.e., medical clinicians, operating room
manager, biomedical engineering staff, and facility safety engineering staff).
•
Choose the specific operating room under consideration. The objective is to determine if
this room should be designated as a wet or dry procedure location under NFPA 99.
•
Identify the functional purpose of the chosen operating room and list the potential liquids
allowed into the room, as well as the potential liquids associated with the patient and
surgical procedure type(s) (e.g., in order of increasing volume, an anesthetic ampoule, a
bag of saline solution, or a container of irrigation fluid).216
•
Select the largest single source of liquid in the operating room. Calculate the pool size of
this volume of liquid (procedure described below):
•
Calculate the total area (wall-to-wall) of the operating room. Subtract the footprint areas
of fixed or portable equipment in the room, not including the operating room table
surface area or other work area. The net open area is the unoccupied area of the
operating room.
216
Typical surgical procedures to be performed in the hospital operating room can be reviewed for estimated blood
loss volumes, estimated body fluids (e.g. IV fluids, urine output), and the use of liquid medications, sterilizers,
and irrigation fluids to support surgical procedures. Medical literature referenced in Section 2.1can be used as
guidance and/or individual medical personnel experience. Liquid containment vessels for suction and blood
recycling should also be included.
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•
Calculate the ratio of the liquid pool area to the unoccupied area of the operating room.
This ratio is defined as the probability of personnel exposure to the liquid release or
simply the probability of exposure.
Note that this algorithm considers only a single-event exposure. This does not contemplate the
multiple exposures an individual may be exposed on an annual basis.
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Figure 2.. Fault tree for an electric shock hazard in a hospital operating room including example liquids and
possible modes of liquid release for consideration in the risk ranking analysis based on spill size
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Figure 3.. Event tree for an electric shock hazard in a hospital operating room for the risk ranking analysis based on spill size
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The fourth edition of the Society of Fire Protection Engineering (SFPE) Handbook includes data
from applicable studies relating pool size to a fixed-quantity, unconfined liquid spill.217 The
intent of the data is to relate a fuel spill volume to the potential pool fire diameter. However, in
addition to various fuels, data for spills of water on concrete and tile floor are provided in Table
2-15.1 and Figure 2-15.4 of the SFPE Handbook 4th Edition; see Figure 4 for a reproduction of
this data. This data is a first order approximation of potential liquids found in a hospital
operating room, which are often water based. Higher order approximations would involve
correlations developed that base pool thickness on physical liquid properties, such as surface
tension and viscosity.218 A higher order correlation was not available at the time this report was
created.
A polynomial trend line was fit to the SFPE Handbook data from water spilled on a concrete
surface from one meter height to determine a first order approximation and correlate the
empirical data to other spilled water volumes. The equation for the polynomial trend line is as
follows:
Equation 1
where Thickness is the pool thickness [mm] and V is the volume of liquid released [L]. This data
set of a fixed volume water spilled from one meter height provides a conservative estimate of
pool diameter as a function of spill volume, as a thinner pool will result in a larger pool diameter
for a given spill volume. The pool diameter as a function of liquid release volume is shown in
Figure 5. The pool diameter assumes a circular pool determined from the pool area, both of
which are calculated as follows:
Equation 2
217
Gottuk DT and White DA “Liquid Fuel Fires” Section 2 Chapter 15 in DiNenno PJ et al, eds. Society of Fire
Protection Engineering Handbook. 4th edition, pg 2-(337-340), 2008.
218
Further experimental data has been performed by Dan Gottuk with publication of a new data set and higher order
correlation anticipated in 2010: Mealy CL, Benfer M, Gottuk DT, “Fire Dynamics and Forensic Analysis of
Liquid Fuel Spill Fires,” Grant No. 2008-DN-BX-K168, Office of Justice Programs, National Institute of Justice,
Department of Justice, 2010 (in preparation).
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Equation 3
where Pool Area is in [m2] and D is the pool diameter [m]. This data set provides a pragmatic
measure to develop liquid release severity categories.
Figure 4. Data presented in the SFPE Handbook 4th Ed., pool thickness as a function of an
unconfined, fixed quantity of water spilled on tile or concrete floor from a discrete
height: (purple circles) water on concrete from 0.5 m height (blue diamonds)
water on concrete from 1 m height, (green triangles) water on tile from 0.15m,
(red squares) water on tile from 0.9 m
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Figure 5. Pool diameter as a function of liquid volume assuming a circular pool as estimated
from the polynomial fit trend line of the SFPE empirical spill data for a spill of
water on concrete from 1 m presented in Figure 4; The blue squares represent
sample volumes of liquid selected in the sample calculation (Table 10) of
probability of exposure
Considering an operating room with an unoccupied area of 50 m2, Table 10 illustrates a sample
calculation on how to evaluate the risk of an unconfined release of a fixed volume of liquid using
the algorithm described above for a single-event exposure.
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Table 10. Sample Calculation for a Single-Event Exposure in a 50 m2 room
Severity Category of
Potential Liquid
Release
Non-existent
Small
Medium
Large
Volume of Liquid
Estimated Pool
Diameter
Probability of
Exposure
(Single Event)
< 75 mL
< 0.30 m (1.0 ft)
< 1.5 E-3
75 mL to 750 mL
0.30 m (1.0 ft) to
0.92 m (3.0 ft)
1.5 E-3 to 1.3 E-2
750 mL to 3000 mL
0.92 m (3.0 ft) to
1.64 m (5.4 ft)
1.3 E-2 to 4.3 E-2
> 3000 mL
> 1.64 m (5.4 ft)
> 4.3 E-2
An overall risk assessment is needed to be able to classify the operating room environment as
wet or dry. Risk is defined as the chance per year that an unprotected person (i.e., the operating
room staff or patient) located at a specific position (i.e., in an operating room in contact with a
faulty electrical device) relative to the risk source (i.e., exposure to a wet environment). The
maximum risk that an individual may be subjected to can be expressed in terms of the greatest
probability that any individual in the operating room may be exposed to a life or health
threatening event (i.e., contact with a conductive liquid leading to electric shock). Using the
above described algorithm, the worst case single-event probability of exposure to a liquid pool in
an operating room can be determined. From this calculation demonstrated in Table 10, the
annual probability of exposure for the operating room can be calculated. The annual probability
of exposure factors in the effect of occupancy (i.e., the utilization of the operating room).
The recommended algorithm to determine annual risk is to multiply the probability of exposure
for a single event (i.e., one surgical procedure in a specific operating room) by the projected
number of procedures that occur in a year in that specific operating room. Table 11 illustrates a
sample calculation comparing a 50 m2 operating room with high utilization to an operating room
of the same size with low utilization for the liquid volumes in the sample calculation presented in
Table 10. An operating room with high utilization was estimated to be four procedures per day,
250 days per year, and an operating room with low utilization was estimated to be one procedure
per day, 25 days per year, for example purposes only.
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Table 11. Sample Calculation to Determine Annual Risk based on the Probability of Exposure to
a Liquid Pool
Severity
Category of
Potential
Liquid
Release
Non-existent
Small
Medium
Large
Probability of Exposure
(Annual Utilization)
Volume of Liquid
High Utilization OR
4 procedures / day
250 days / year
Low Utilization OR
1 procedure / day
25 days / year
< 75 mL
< 1.5
< .037
75 mL to 750 mL
1.5 to 13.4
.037 to .33
750 mL to 3000 mL
13.4 to 42.5
.33 to 1.06
> 3000 mL
> 42.5
> 1.06
An annual probability of exposure of greater than or equal to one means that exposure to a liquid
pool is certain. To interpret the results of the Table 11 sample calculation for the operating room
with high utilization, the annual risk of exposure to a liquid pool is more likely than not if there
are any volumes of liquids present that are on the order of 75 mL.219 With this sample scenario,
there are many opportunities for exposure, and therefore the operating room should be classified
as a wet procedure location. For the operating room with low utilization, volumes of liquid up to
750 mL can be regularly present and the operating room classified as a dry location.
The High/Low Utilization OR classification used in Table 11 is one possible way to quantify the
utilization of an operating room, but other methods can be used. For example, if there is
sufficient data available, the number of procedures per day can be modified to reflect the number
of long time duration procedures that occur in the operating room in question.
219
For the high utilization sample scenario, the volume of liquid should be less than 50 mL in order to not lead to
certain exposure.
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Summary
The motivation for this study is to provide a comprehensive view of the hospital operating room
electrical environment in order to facilitate a risk analysis by an individual hospital, to establish
whether a particular operating room should have a “wet procedure location” or “dry location”
electrical classification.
A literature review was performed to address the electrical classification of hospital operating
rooms, which focused on hazards resulting in electric shock to occupants. Environmental
conditions in the operating room were found to vary based on operational factors, such as the
type of surgery or procedure being performed, and use of irrigation fluid. The data presented
does not give a complete quantification of the amounts of fluids present in the operating room or
the probability of a liquid release, but represents a survey of the available literature.
A review of adverse event reporting in the medical industry reveals that reporting systems have
been under development in the US for only the past 10 years, with only slightly more than half of
the states with reporting systems in place to track adverse events. It has also been identified that
practitioners in the healthcare industry resist reporting adverse events due to a fear of
disciplinary action, which shifts the focus away from utilizing the databases to establish a culture
of safety by calling attention to root causes and improving training in certain areas to improve
patient safety.
A gap analysis of the literature addresses data to evaluate an operating room as a wet or dry
location, adverse event and incident reporting, and information about the current electrical
systems used in the medical industry. Consistent standards of adverse event classification,
analysis, and reporting are not implemented, however, the AHRQ is in the process of
implementing and maintaining a national network of databases, with the first results anticipated
in 2011.
A risk assessment method is proposed for hospitals to use in order to evaluate the proper
classification of an operating room. The recommended model is a risk ranking method based on
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the volume of a potential spill or liquid release and the subsequent liquid pool size as determined
from empirical liquid spill data onto hard surfaces published in the SFPE Handbook, 4th edition.
This method determines the annual probability of exposure to a liquid pool in an operating room.
A sample calculation is demonstrated for a range of liquid volumes in an average size hospital
operating room with both high and low utilization.
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